{
  "spore": "profile",
  "id": "molybdenum-disilicide",
  "spore_version": "0.2",
  "family": "carbide-nitride-boride-ceramics",
  "name": "Molybdenum disilicide",
  "abbreviation": "MoSi2",
  "role": "high-temperature electric heating element material (dense silicide cermet, sold as Kanthal Super)",
  "category": "ceramics",
  "type": "ultra-high-temperature-ceramics",
  "summary": "Molybdenum disilicide is a dense cermet of MoSi2 with a mainly glass phase, sold as Kanthal Super heating elements. Kanthal's datasheets give a density of 5.6 g/cm3 for Super 1700 and 6.5 g/cm3 for Super 1900, a bending strength of 450 MPa at 20 degC, a Vickers hardness of 9 GPa and a fracture toughness of 3 to 4 MPa·m1/2. The maximum operating temperature in air is 1700 degC for Super 1700 and 1850 degC for Super 1900. The material forms a quartz-glass layer that protects it from oxidation, but Kanthal says it is brittle below about 1200 degC, and surface oxidation near 500 degC gives a yellowish MoO3 powder. NACA measured room-temperature electrical resistivity at 23 to 27 microohm-cm in 1952. Molybdenum, one of its two elements, is produced mostly in China, Chile, the United States, Peru and Mexico (USGS 2026).\n",
  "best_for": "Electric heating elements in air furnaces for heat treatment, forging, sintering and glass melting, at element temperatures up to about 1700 to 1850 degC",
  "weakest_at": "Brittleness below about 1200 degC (Kanthal), and low-temperature oxidation near 500 degC that forms yellowish MoO3 powder",
  "identity": {
    "formula": "MoSi2",
    "cas": "12136-78-6",
    "designations": [],
    "source": "pubchem-mosi2",
    "where": "PubChem CID 6336985 record (MolecularFormula MoSi2, MolecularWeight 152.12). CAS 12136-78-6 from Section 3 of the Stanford Advanced Materials SDS (stanford-sds)."
  },
  "tags": {
    "environments": [],
    "stresses": [
      "extreme-heat"
    ],
    "applications": [
      "in-space-manufacturing",
      "structures"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, Kanthal Super 1700",
      "value": 5.6,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "grade": "Kanthal Super 1700",
        "printed": "5.6 (0.20) g/cm3 (lbs/in3)"
      },
      "method": "Physical properties table, density row, Kanthal Super 1700 datasheet (updated 2010-05-11)",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Physical properties table, Density row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, Kanthal Super 1900",
      "value": 6.5,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "grade": "Kanthal Super 1900",
        "printed": "6.5 (0.23) g/cm3"
      },
      "method": "Physical properties table, density row, Kanthal Super 1900 product page",
      "status": "ground",
      "note": "The Kanthal handbook prints 6.5 g/cm3 for the 'other Kanthal Super' column, which is not the same table as the Super 1700 datasheet (5.6 g/cm3). Both are kept with their grade.",
      "source": "kanthal-super-1900",
      "where": "Physical properties table, Density row",
      "source_detail": {
        "title": "Kanthal Super 1900, material datasheet page (kanthal.com)",
        "url": "https://kanthal.com/en/products/material-datasheets/ceramic-elements/molybdenum-disilicide/kanthal-super-1900",
        "kind": "datasheet",
        "license": "Kanthal product page; cited, not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Relative density (supplier SDS)",
      "value": 6.31,
      "bound": "exact",
      "unit": "g/mL",
      "scope": "material",
      "conditions": {
        "temperature": "25 degC",
        "grade": "not stated"
      },
      "method": "Relative density in Section 9 of the supplier SDS, printed as 6.31 g/mL at 25 degC (numerically equal to g/cm3)",
      "status": "ground",
      "note": "Supplier SDS value; grade and form are not stated in the SDS.",
      "source": "stanford-sds",
      "where": "Section 9, Relative density",
      "source_detail": {
        "title": "Stanford Advanced Materials, Safety Data Sheet, Molybdenum Silicide (MoSi2), revised 04/02/2023",
        "url": "https://samaterials.com/tds/1697120333-803-molybdenum-silicide-evaporation-materials-sds.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Maximum operating temperature in air, Kanthal Super 1700",
      "value": 1700,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "atmosphere": "air",
        "grade": "Kanthal Super 1700"
      },
      "method": "Last row of the Super 1700 physical properties table",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Physical properties table, Maximum operating temperature in air row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Maximum operating temperature in air, Kanthal Super 1900",
      "value": 1850,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "atmosphere": "air",
        "grade": "Kanthal Super 1900"
      },
      "method": "Maximum operating temperature in air row, Kanthal Super 1900 product page",
      "status": "ground",
      "source": "kanthal-super-1900",
      "where": "Physical properties table, Maximum operating temperature in air row",
      "source_detail": {
        "title": "Kanthal Super 1900, material datasheet page (kanthal.com)",
        "url": "https://kanthal.com/en/products/material-datasheets/ceramic-elements/molybdenum-disilicide/kanthal-super-1900",
        "kind": "datasheet",
        "license": "Kanthal product page; cited, not reproduced"
      }
    },
    {
      "benchmark": "hardness",
      "label": "Vickers hardness HV, Kanthal Super 1700 and 1900",
      "value": 9,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "20 degC",
        "basis": "HV value printed for Super 1700; the same value is printed on the Super 1900 product page"
      },
      "method": "Hardness HV row of the mechanical properties table",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Mechanical properties table, Hardness HV row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Bending strength, Kanthal Super 1700 and 1900",
      "value": 450,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temperature": "20 degC",
        "grade": "Kanthal Super 1700 (Super 1900 page prints the same value)"
      },
      "method": "Bending strength row of the mechanical properties table",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Mechanical properties table, Bending strength row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "compressive_strength",
      "label": "Compression strength, Kanthal Super (all grades except ER and HT in the table)",
      "value": 1400,
      "value_high": 1500,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temperature": "20 degC",
        "grade": "Kanthal Super family, handbook table column for other grades"
      },
      "method": "Compression strength row of the Kanthal Super mechanical and physical properties table (handbook)",
      "status": "ground",
      "source": "kanthal-handbook",
      "where": "Table 'The mechanical and physical properties of Kanthal Super', Compression strength row",
      "source_detail": {
        "title": "Kanthal Super electric heating elements handbook (English, super-handbook_b_eng.pdf)",
        "url": "https://prodshop.kanthal.com/globalassets/kanthal-global/downloads/super-handbook_b_eng.pdf",
        "kind": "handbook",
        "license": "Kanthal handbook; cited, not reproduced"
      }
    },
    {
      "benchmark": "fracture_toughness",
      "label": "Fracture toughness KIC, Kanthal Super 1700",
      "value": 3,
      "value_high": 4,
      "bound": "range",
      "unit": "MPa·m1/2",
      "scope": "material",
      "conditions": {
        "temperature": "20 degC",
        "grade": "Kanthal Super 1700"
      },
      "method": "Fracture toughness KIC row of the mechanical properties table, printed as 3-4 MPa√m",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Mechanical properties table, Fracture toughness KIC row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength at 1500 degC, Kanthal Super 1700 and 1900",
      "value": 100,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temperature": "1500 degC (2820 degF)",
        "grade": "Kanthal Super 1700 datasheet and Super 1900 page"
      },
      "method": "Tensile strength at elevated temperatures table",
      "status": "ground",
      "note": "The handbook prints 100 MPa +/- 25 percent at 1550 degC for another group of grades. The temperatures differ, so both rows are kept.",
      "source": "kanthal-super-1700",
      "where": "Tensile strength at elevated temperatures table, 1500 (2820) row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength at 1550 degC, Kanthal Super HT and other grades (handbook)",
      "value": 100,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temperature": "1550 degC (2820 degF)",
        "tolerance": "+/- 25 percent",
        "grade": "Kanthal Super HT and other grades in the handbook table"
      },
      "method": "Tensile strength at 1550 degC row of the Kanthal Super mechanical and physical properties table",
      "status": "ground",
      "source": "kanthal-handbook",
      "where": "Table 'The mechanical and physical properties of Kanthal Super', Tensile strength row",
      "source_detail": {
        "title": "Kanthal Super electric heating elements handbook (English, super-handbook_b_eng.pdf)",
        "url": "https://prodshop.kanthal.com/globalassets/kanthal-global/downloads/super-handbook_b_eng.pdf",
        "kind": "handbook",
        "license": "Kanthal handbook; cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, 20 to 600 degC",
      "value": 30,
      "bound": "exact",
      "unit": "W/m·K",
      "scope": "material",
      "conditions": {
        "temperature": "20 to 600 degC (68 to 1110 degF)",
        "grade": "Kanthal Super 1700"
      },
      "method": "Thermal conductivity row, first temperature band",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Physical properties table, Thermal conductivity row, 20-600 degC column",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, 600 to 1200 degC",
      "value": 15,
      "bound": "exact",
      "unit": "W/m·K",
      "scope": "material",
      "conditions": {
        "temperature": "600 to 1200 degC (1110 to 2190 degF)",
        "grade": "Kanthal Super 1700"
      },
      "method": "Thermal conductivity row, second temperature band",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Physical properties table, Thermal conductivity row, 600-1200 degC column",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of linear expansion, Kanthal Super 1700",
      "value": 7,
      "value_high": 8,
      "bound": "range",
      "unit": "10-6/K",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the datasheet row",
        "grade": "Kanthal Super 1700"
      },
      "method": "Coefficient of linear expansion row, printed as 7-8 10-6/K",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Physical properties table, Coefficient of linear expansion row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, Kanthal Super 1700",
      "value": 0.42,
      "bound": "exact",
      "unit": "kJ/kg·K",
      "scope": "material",
      "conditions": {
        "temperature": "20 degC (68 degF)",
        "grade": "Kanthal Super 1700"
      },
      "method": "Specific heat capacity at 20 degC row",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Physical properties table, Specific heat capacity row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "porosity",
      "label": "Porosity, Kanthal Super 1700",
      "value": 1,
      "bound": "upper",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "Kanthal Super 1700"
      },
      "method": "Porosity row, printed as less than 1 percent",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Physical properties table, Porosity row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "emissivity",
      "label": "Emissivity, Kanthal Super 1700",
      "value": 0.7,
      "value_high": 0.8,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "Kanthal Super 1700"
      },
      "method": "Emissivity row, printed as 0.70-0.80",
      "status": "ground",
      "source": "kanthal-super-1700",
      "where": "Physical properties table, Emissivity row",
      "source_detail": {
        "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
        "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
        "kind": "datasheet",
        "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity at room temperature, MoSi2 (NACA 1952)",
      "value": 23,
      "value_high": 27,
      "bound": "range",
      "unit": "uOhm·cm",
      "scope": "material",
      "conditions": {
        "temperature": "room temperature",
        "basis": "depends on the method of fabrication; NACA printed microhm-centimeters"
      },
      "method": "Summary, third paragraph; the memo says the conductivity is metallic and decreases with temperature up to 2000 degF",
      "status": "ground",
      "source": "naca-rm-e52a04",
      "where": "Summary, third paragraph",
      "source_detail": {
        "title": "Maxwell, W. A., Oxidation-Resistance Mechanism and Other Properties of Molybdenum Disilicide, NACA RM E52A04 (1952)",
        "url": "https://ntrs.nasa.gov/api/citations/19930086994/downloads/19930086994.pdf",
        "kind": "report",
        "license": "public domain (NASA NTRS)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Modulus of elasticity at room temperature, MoSi2 (NACA 1952, dynamic method)",
      "value": 59,
      "bound": "exact",
      "unit": "psi x 10^6",
      "scope": "material",
      "conditions": {
        "temperature": "room temperature",
        "method_detail": "dynamic method"
      },
      "method": "Summary, fourth paragraph; printed as 59 x 10^6 pounds per square inch. Kept in the printed unit, so the importer converts it. The memo also says poor damping characteristics at room temperature.",
      "status": "ground",
      "source": "naca-rm-e52a04",
      "where": "Summary, third paragraph",
      "source_detail": {
        "title": "Maxwell, W. A., Oxidation-Resistance Mechanism and Other Properties of Molybdenum Disilicide, NACA RM E52A04 (1952)",
        "url": "https://ntrs.nasa.gov/api/citations/19930086994/downloads/19930086994.pdf",
        "kind": "report",
        "license": "public domain (NASA NTRS)"
      }
    },
    {
      "benchmark": "ignition_temperature",
      "label": "Ignition temperature of MoSi2 powder in air",
      "value": 405,
      "value_high": 510,
      "bound": "range",
      "unit": "degF",
      "scope": "material",
      "conditions": {
        "form": "powder",
        "basis": "small samples rapidly heated in a furnace; 510 degF for 3.0 g and 405 degF for 20.0 g"
      },
      "method": "Results, Oxidation of powdered MoSi2, first paragraph",
      "status": "ground",
      "note": "Custom property name. Powder property, not a bulk property.",
      "source": "naca-rm-e52a04",
      "where": "Results, Oxidation of powdered MoSi2, first paragraph",
      "source_detail": {
        "title": "Maxwell, W. A., Oxidation-Resistance Mechanism and Other Properties of Molybdenum Disilicide, NACA RM E52A04 (1952)",
        "url": "https://ntrs.nasa.gov/api/citations/19930086994/downloads/19930086994.pdf",
        "kind": "report",
        "license": "public domain (NASA NTRS)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Air at about 500 degC (930 degF), low-temperature oxidation (pest)",
      "headline": "Molybdenum and silicon on the surface oxidise to a yellowish MoO3 powder. The handbook says this normally has no detrimental effect.",
      "effect": "Kanthal says oxidation of molybdenum and silicon on the surface of the elements can occur at temperatures around 500 degC (930 degF). The product is a yellowish powder, MoO3, which normally has no detrimental effect on performance. In the separate note on aluminised elements, the handbook adds that pest under the aluminising means the temperature has been far too high.",
      "rating": "low",
      "conditions": {
        "temperature": "about 500 degC (930 degF)",
        "atmosphere": "air"
      },
      "source": "kanthal-handbook",
      "where": "Section 'Air' under the atmosphere guidance, and the note on loose contacts and pest"
    },
    {
      "environment": "Air at high temperature (protective quartz-glass layer)",
      "headline": "A thin quartz-glass layer forms on the surface, protecting the material up to the rated element temperature.",
      "effect": "Kanthal says Super elements withstand oxidation at high temperature because a thin, adhesive protective layer of quartz glass forms on the surface. NACA (1952) identified the protective coating on oxidised MoSi2 as cristobalite. Kanthal's datasheet calls the material resistant to corrosion and oxidation.",
      "rating": "low",
      "conditions": {
        "temperature": "up to 1700 to 1850 degC element temperature in air (Super 1700 and 1900)",
        "atmosphere": "air"
      },
      "source": "kanthal-handbook",
      "where": "Introduction page, text on oxidation resistance (THIS IS KANTHAL SUPER)"
    },
    {
      "environment": "Furnace atmospheres containing water vapour or carbon dioxide",
      "headline": "Water vapour and carbon dioxide act as oxidising agents. The size of the effect is not given in the part read.",
      "effect": "The handbook states that water vapour and carbon dioxide in any amount in the atmosphere have an oxidising effect. The rest of the atmosphere guidance was not reviewed in this pass, so no rate or temperature limit is given here.",
      "rating": "unknown",
      "conditions": {
        "atmosphere": "furnace atmosphere containing water vapour or carbon dioxide"
      },
      "source": "kanthal-handbook",
      "where": "Atmosphere guidance, 'Water vapor and carbon dioxide' paragraph"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem aggregated GHS for molybdenum disilicide (CID 6336985, signal word Warning): H302 (74.5 percent of reports), H312 (74.5 percent) and H332 (74.5 percent). 25.5 percent (13 of 51 reports) say the substance does not meet GHS hazard criteria.",
        "ghs": [
          "H302",
          "H312",
          "H332"
        ],
        "source": "pubchem-mosi2",
        "where": "Safety and Hazards, GHS Classification"
      },
      {
        "text": "Supplier SDS (Stanford Advanced Materials, revised 04/02/2023): acute toxicity category 4 by oral, dermal and inhalation routes; H302 + H312 + H332 harmful if swallowed, in contact with skin or if inhaled; signal word Warning.",
        "ghs": [
          "H302",
          "H312",
          "H332"
        ],
        "source": "stanford-sds",
        "where": "Section 2, GHS Classification and Label elements"
      }
    ],
    "failure_risks": [
      {
        "mode": "Brittle fracture below about 1200 degC",
        "trigger": "Mechanical load or thermal stress on an element operated below about 1200 degC",
        "consequence": "Kanthal says the material is more brittle at lower temperatures and becomes ductile around 1200 degC. The Super 1700 datasheet gives a bending strength of 450 MPa and a fracture toughness of 3 to 4 MPa·m1/2 at 20 degC.",
        "severity": "moderate",
        "source": "kanthal-super-1700",
        "where": "Mechanical properties table; Introduction page (ductile at about 1200 degC)"
      },
      {
        "mode": "Element failure from carbon build-up in a carburising furnace",
        "trigger": "High carbon potential in a carburising atmosphere, with element temperature normally kept below 1400 degC",
        "consequence": "Kanthal says that carbon build-up in the furnace can lead to element failure, and recommends regular removal of the carbon by firing the furnace under oxidising conditions.",
        "severity": "moderate",
        "source": "kanthal-handbook",
        "where": "Section 'Carburizing atmosphere'"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Powder: NACA (1952) says that in powdered form MoSi2 is not inherently resistant to oxidation and burns in air at comparatively low temperatures. Ignition temperatures were 510 degF (3.0 g sample) and 405 degF (20.0 g sample). A 5-pound quantity held at 212 degF overnight oxidised completely.",
        "source": "naca-rm-e52a04",
        "where": "Results, Oxidation of powdered MoSi2, first paragraph"
      },
      {
        "text": "Powder dust: the supplier SDS says to avoid dust formation, to avoid breathing dust and to provide exhaust ventilation where dust is formed.",
        "source": "stanford-sds",
        "where": "Section 7 (handling) and Section 8 (exposure controls)"
      },
      {
        "text": "PubChem lists H302, H312 and H332 for the compound. Avoid swallowing it, skin contact and breathing the dust.",
        "source": "pubchem-mosi2",
        "where": "Safety and Hazards, GHS Classification"
      }
    ],
    "mitigations": [
      {
        "text": "Kanthal recommends keeping the element temperature normally below 1400 degC in carburising furnaces, and removing carbon build-up regularly by firing the furnace under oxidising conditions.",
        "source": "kanthal-handbook",
        "where": "Section 'Carburizing atmosphere'"
      }
    ]
  },
  "uses": [
    {
      "application": "in-space-manufacturing",
      "device": "Electric heating elements for industrial furnaces (heat treatment, forging, sintering and glass melting)",
      "example": "Kanthal says typical application for Super 1700 includes most types of industrial furnace for heat treatment, forging, sintering, glass melting and refining, and for radiant tubes. This is a terrestrial furnace use; the application tag is the nearest item in the list, and no space furnace use was read.",
      "source": "kanthal-super-1700",
      "where": "Introduction page, 'Typical area of application' paragraph"
    },
    {
      "application": "structures",
      "device": "Oxidation-protective silicide coatings on molybdenum (research only)",
      "example": "NACA (1952) says silicon-containing coatings, which appear to derive their oxidation resistance from the presence of MoSi2, offer considerable promise for protecting molybdenum at high temperatures. This is a research statement, not a production use.",
      "source": "naca-rm-e52a04",
      "where": "Introduction, second paragraph"
    }
  ],
  "supply": [
    {
      "subject": "Molybdenum (the molybdenum half of MoSi2)",
      "abundance": "USGS: identified molybdenum resources are about 5.4 million tons in the United States and about 20 million tons in the rest of the world, and are adequate to supply world needs for the foreseeable future. World reserves are 17,000 thousand tons (2025, as printed).",
      "producers": [
        {
          "country": "China",
          "share_percent": 37.3,
          "year": 2025
        },
        {
          "country": "Chile",
          "share_percent": 16.2,
          "year": 2025
        },
        {
          "country": "United States",
          "share_percent": 15.4,
          "year": 2025
        },
        {
          "country": "Peru",
          "share_percent": 15,
          "year": 2025
        },
        {
          "country": "Mexico",
          "share_percent": 6.5,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals (final list of 60 minerals; molybdenum is not on it)",
          "listed": false
        },
        {
          "list": "EU critical raw materials list (Regulation (EU) 2024/1252, European Commission page; molybdenum is not in the list read)",
          "listed": false
        }
      ],
      "recycling": "USGS: molybdenum is recycled as a component of catalysts, ferrous scrap and superalloy scrap.",
      "substitutes": [
        "USGS: potential substitutes for refractory materials in high-temperature electric furnaces are graphite, tantalum and tungsten."
      ],
      "source": "usgs-mcs2026-molybdenum",
      "where": "World Mine Production and Reserves table, 2025e column (world total 260,000 t, rounded; shares calculated by Space Mushroom as country output over that total); Events, Trends and Issues (China export controls on molybdenum powders, February 2025); Recycling; Substitutes"
    },
    {
      "subject": "Silicon (the silicon half of MoSi2, as silicon metal)",
      "abundance": "USGS: China accounted for almost 80 percent of total global estimated production of silicon materials (ferrosilicon and silicon metal) in 2025. Silicon metal world production in 2025 was 4,600 thousand tons (rounded, as printed).",
      "producers": [
        {
          "country": "China",
          "share_percent": 87,
          "year": 2025
        },
        {
          "country": "Brazil",
          "share_percent": 3.9,
          "year": 2025
        },
        {
          "country": "Norway",
          "share_percent": 2.8,
          "year": 2025
        },
        {
          "country": "France",
          "share_percent": 1.5,
          "year": 2025
        },
        {
          "country": "Australia",
          "share_percent": 1,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals (silicon added in the final 2025 list)",
          "listed": true
        },
        {
          "list": "EU critical raw materials list (Regulation (EU) 2024/1252, silicon metal, European Commission page)",
          "listed": true
        }
      ],
      "recycling": "USGS: insignificant.",
      "substitutes": [
        "USGS: gallium arsenide and germanium are the principal substitutes for silicon in semiconductor and infrared applications. No substitute for silicon in MoSi2 is discussed."
      ],
      "source": "usgs-mcs2026-silicon",
      "where": "World Production table, silicon metal 2025 column (world total 4,600 thousand tons, rounded; shares calculated by Space Mushroom); Events, Trends and Issues; critical minerals paragraph; Recycling; Substitutes"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, copy hosted on ibt.co.il, updated 2010-05-11",
      "type": "datasheet",
      "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
      "year": 2010
    },
    {
      "title": "Kanthal Super 1900 product datasheet page (kanthal.com)",
      "type": "datasheet",
      "url": "https://kanthal.com/en/products/material-datasheets/ceramic-elements/molybdenum-disilicide/kanthal-super-1900",
      "year": 2026
    },
    {
      "title": "Kanthal Super electric heating elements handbook (English)",
      "type": "datasheet",
      "url": "https://prodshop.kanthal.com/globalassets/kanthal-global/downloads/super-handbook_b_eng.pdf"
    },
    {
      "title": "Maxwell, W. A., NACA RM E52A04, Oxidation-Resistance Mechanism and Other Properties of Molybdenum Disilicide (1952)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19930086994/downloads/19930086994.pdf",
      "year": 1952
    },
    {
      "title": "Stanford Advanced Materials, Safety Data Sheet, Molybdenum Silicide (MoSi2), revised 04/02/2023",
      "type": "sds",
      "url": "https://samaterials.com/tds/1697120333-803-molybdenum-silicide-evaporation-materials-sds.pdf",
      "year": 2023
    },
    {
      "title": "PubChem compound record CID 6336985, molybdenum disilicide (GHS classification)",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/6336985",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026, Molybdenum",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026, Silicon",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf",
      "year": 2026
    }
  ],
  "gaps": [
    "Melting point not found in this pass. The OSTI record for the Kanthal-era review (2030 degC in a search snippet) was not readable, and the DTIC report returned an error page. No melting value is in the file.",
    "Crystal system and space group not found in this pass, so identity has no crystal_system or space_group.",
    "Designations: only the trade-name family 'Kanthal Super' is printed in a source read in this run. UNS, EN, DIN, JIS and AISI codes were not found. The Super grades 1700, 1800, 1900, HT, RA and ER are different grades and are not listed as designations.",
    "Density conflict: 5.6 g/cm3 (Super 1700 datasheet), 6.5 g/cm3 (Super 1900 page and the handbook's other-grades column), 7.0 g/cm3 (Super HT, handbook) and 6.31 g/mL (supplier SDS, grade not stated). All are kept with their grade or source.",
    "Tensile strength temperature conflict: the Super 1700 datasheet prints 100 MPa at 1500 degC, the handbook prints 100 MPa +/- 25 percent at 1550 degC for other grades. Both are kept.",
    "Super HT grade (bending strength 350 to 400 MPa, density 7.0 g/cm3, porosity below 1 percent) is in the handbook but not included, because the file covers the Super 1700 and 1900 grades.",
    "Pest (low-temperature oxidation) window: only 'around 500 degC' is printed by the handbook. The McKamey and Meschter papers on pest oxidation (Cambridge and scholarhub.vn abstracts) were paywalled or not readable, so no pest temperature range or rate is recorded.",
    "Open-access MoSi2 review or paper giving a melting point, hardness at temperature, or oxidation rates was not opened in this run. The MDPI Materials 2026 article (doi 10.3390/ma19081653) returned HTTP 403 and the Torino repository copy returned an HTML page, so neither is used.",
    "Custom property names used because they are not in spores/property-canon.yaml: hardness, compressive_strength, fracture_toughness, porosity, emissivity, ignition_temperature.",
    "Space use: no NASA, ESA or flight source for MoSi2 heating elements or coatings was read. The NACA 1952 memo is laboratory research. No vacuum, radiation or atomic-oxygen data were read.",
    "Hazard data rest on the PubChem aggregate and one supplier SDS. The SDS lists no melting point, and its toxicology section was not checked in this run.",
    "Supply shares: molybdenum shares are calculated against the rounded 260,000 t world total (country values sum to 259,900 t). Silicon shares are calculated against the rounded 4,600 thousand t silicon-metal total. Both are Space Mushroom calculations, not USGS figures.",
    "The EU critical raw materials page read does not explicitly confirm the annex contents of Regulation (EU) 2024/1252. Molybdenum is absent and silicon metal is listed on the page read.",
    "Crustal abundance of molybdenum and silicon not found in this pass.",
    "The NACA memo sentence pairs the two ignition temperatures (510 degF and 405 degF) with the 3.0 g and 20.0 g samples in order, and that order is used here."
  ],
  "story": {
    "why": "Molybdenum disilicide is a silicide cermet used for electric heating elements in high-temperature air furnaces. Its surface forms a quartz-glass layer that resists oxidation, so the element can run at up to about 1700 to 1850 degC according to Kanthal's grade table. The same material is brittle at lower temperatures, so element handling and the temperature band both matter. The sources read here give a bending strength of 450 MPa, a density of 5.6 to 6.5 g/cm3 depending on grade, and a room-temperature electrical resistivity of 23 to 27 microohm-cm (NACA 1952).",
    "uses": [
      {
        "where": "Industrial furnaces",
        "line": "Kanthal says Super 1700 elements are used in most types of industrial furnace for heat treatment, forging, sintering, glass melting and refining, and in radiant tubes."
      },
      {
        "where": "Oxidation-protective coatings (research)",
        "line": "NACA (1952) reported that silicon-containing coatings, which derive their oxidation resistance from MoSi2, look promising for protecting molybdenum at high temperature. This is a research finding, not a production use."
      },
      {
        "where": "Space applications",
        "line": "No flight, space or lunar source for MoSi2 heating elements was read in this run."
      }
    ],
    "can_do": [
      {
        "label": "Heat in air",
        "line": "Kanthal gives a maximum operating temperature in air of 1700 degC for Super 1700 and 1850 degC for Super 1900.",
        "benchmark": "max_service_temp",
        "scope": "material",
        "value": "1850 degC"
      },
      {
        "label": "Stiffness",
        "line": "NACA (1952) measured a room-temperature modulus of elasticity of 59 x 10^6 psi by a dynamic method. It also notes poor damping at room temperature.",
        "benchmark": "elastic_modulus",
        "scope": "material"
      },
      {
        "label": "Hardness",
        "line": "Kanthal gives a Vickers hardness HV of 9 GPa for Super 1700 and Super 1900.",
        "benchmark": "hardness",
        "scope": "material",
        "value": "9 GPa"
      },
      {
        "label": "Heat conduction",
        "line": "Kanthal gives 30 W/m·K from 20 to 600 degC and 15 W/m·K from 600 to 1200 degC for Super 1700.",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "30 W/m·K"
      }
    ],
    "compare": "No other heating-element material was read in this run, so this profile does not rank MoSi2 against silicon carbide, FeCrAl or other furnace materials. Within this profile, Super 1700 has a density of 5.6 g/cm3 and a maximum operating temperature in air of 1700 degC, and Super 1900 has a density of 6.5 g/cm3 and 1850 degC.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Maximum operating temperature in air",
        "benchmark": "max_service_temp",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "handling": [
      "Powder: PubChem lists H302, H312 and H332 for the compound. Avoid swallowing it, skin contact and breathing the dust.",
      "Powder ignition: NACA found that the powder ignites in air at 405 to 510 degF, depending on sample size, and that a 5-pound quantity held at 212 degF oxidised completely overnight.",
      "Furnace: keep carburising-furnace element temperature normally below 1400 degC and remove carbon build-up by firing under oxidising conditions (Kanthal)."
    ],
    "good_for": [
      "High-temperature furnace elements in air. Kanthal gives a maximum operating temperature in air of 1700 degC (Super 1700) and 1850 degC (Super 1900).",
      "Hard, stiff ceramic parts at room temperature. Kanthal gives a Vickers hardness of 9 GPa and NACA gives a modulus of 59 x 10^6 psi."
    ],
    "watch_out": [
      "Brittleness below about 1200 degC. Kanthal gives a bending strength of 450 MPa and a fracture toughness of 3 to 4 MPa·m1/2 at 20 degC.",
      "Low-temperature oxidation near 500 degC, which forms yellowish MoO3 powder.",
      "Density differs by grade, from 5.6 g/cm3 (Super 1700 datasheet) to 6.5 g/cm3 (Super 1900 page). Use the grade's own datasheet.",
      "No space, radiation or vacuum data were read."
    ],
    "verdict": "Molybdenum disilicide is a high-temperature furnace heating-element material. It is rated to 1700 to 1850 degC in air and protects itself with a quartz-glass layer, but it is brittle below about 1200 degC and its powder ignites at low temperature. The sourced uses are terrestrial industrial furnaces, and no space application was found.",
    "recipe": {
      "line": "MoSi2 has one molybdenum atom and two silicon atoms per formula unit (PubChem, MolecularFormula MoSi2). NACA made the compound by combining the elements directly, grinding the raw material in water, then leaching it with acids and caustic and drying it in vacuum. Kanthal's commercial element is a dense cermet of MoSi2 with an oxide component, mainly a glass phase.",
      "parts": [
        {
          "name": "Molybdenum",
          "symbol": "Mo",
          "role": "The metal atom in the compound. Molybdenum and silicon together form the MoSi2 phase that gives the element its high-temperature strength and conductivity.",
          "atoms": 1,
          "atomic_weight": 95.95
        },
        {
          "name": "Silicon",
          "symbol": "Si",
          "role": "Forms the protective quartz-glass layer on the surface, which is what protects the element against oxidation in air at high temperature.",
          "atoms": 2,
          "atomic_weight": 28.085
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "Both the PubChem aggregate and a supplier SDS give H302, H312 and H332 with the signal word Warning. PubChem also records that 25.5 percent of reports say the substance does not meet GHS criteria. The supplier SDS lists no melting point.",
        "points": [
          {
            "label": "Dust",
            "line": "The supplier SDS says to avoid dust formation and to provide exhaust ventilation where dust is formed."
          },
          {
            "label": "Powder",
            "line": "NACA (1952) found that powdered MoSi2 burns in air at comparatively low temperatures, with ignition at 405 and 510 degF depending on sample size."
          }
        ],
        "level": 0,
        "verdict": "Harmful if swallowed, in contact with skin or if inhaled…"
      },
      {
        "title": "If an element fails",
        "lead": "These points come from Kanthal's datasheets and handbook, and from the 1952 NACA memo.",
        "points": [
          {
            "label": "Brittleness",
            "line": "Kanthal says the material is brittle below about 1200 degC and becomes ductile around that temperature. Bending strength is 450 MPa at 20 degC."
          },
          {
            "label": "Low-temperature oxidation",
            "line": "Around 500 degC the surface can oxidise to a yellowish MoO3 powder. Kanthal says this normally does not harm performance."
          },
          {
            "label": "Carburising furnaces",
            "line": "Carbon build-up in the furnace can lead to element failure. Kanthal recommends regular removal by firing under oxidising conditions."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 20,
    "unreachable": 3,
    "caveats": 6,
    "note": "Written in this run from the Kanthal Super 1700 datasheet, the Kanthal Super 1900 page, the Kanthal handbook, NACA RM E52A04 (1952), the Stanford Advanced Materials SDS, PubChem CID 6336985, USGS MCS 2026 molybdenum and silicon, the USGS 2025 critical-minerals page and the European Commission list page. Not reachable: OSTI 364016 (connection refused), DTIC AD0408003 (error page), the MDPI Materials 2026 article (403) and the Springer pest-oxidation paper (paywall redirect). verify-values: 20 of 20 values found in their cited sources."
  },
  "sources": {
    "kanthal-super-1700": {
      "title": "Kanthal Super 1700 (Molybdenum disilicide) datasheet, updated 2010-05-11",
      "url": "https://www.ibt.co.il/uploaded_files/documents/datasheet-kanthal-super-1700_U1212.pdf",
      "kind": "datasheet",
      "license": "Kanthal datasheet, copy hosted on ibt.co.il; cited, not reproduced"
    },
    "kanthal-super-1900": {
      "title": "Kanthal Super 1900, material datasheet page (kanthal.com)",
      "url": "https://kanthal.com/en/products/material-datasheets/ceramic-elements/molybdenum-disilicide/kanthal-super-1900",
      "kind": "datasheet",
      "license": "Kanthal product page; cited, not reproduced"
    },
    "kanthal-handbook": {
      "title": "Kanthal Super electric heating elements handbook (English, super-handbook_b_eng.pdf)",
      "url": "https://prodshop.kanthal.com/globalassets/kanthal-global/downloads/super-handbook_b_eng.pdf",
      "kind": "handbook",
      "license": "Kanthal handbook; cited, not reproduced"
    },
    "naca-rm-e52a04": {
      "title": "Maxwell, W. A., Oxidation-Resistance Mechanism and Other Properties of Molybdenum Disilicide, NACA RM E52A04 (1952)",
      "url": "https://ntrs.nasa.gov/api/citations/19930086994/downloads/19930086994.pdf",
      "kind": "report",
      "license": "public domain (NASA NTRS)"
    },
    "stanford-sds": {
      "title": "Stanford Advanced Materials, Safety Data Sheet, Molybdenum Silicide (MoSi2), revised 04/02/2023",
      "url": "https://samaterials.com/tds/1697120333-803-molybdenum-silicide-evaporation-materials-sds.pdf",
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "pubchem-mosi2": {
      "title": "PubChem compound CID 6336985, molybdenum disilicide (GHS classification, aggregated notifications)",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/6336985",
      "kind": "database",
      "license": "PubChem public database"
    },
    "pubchem-mo": {
      "title": "PubChem compound CID 23932, molybdenum (MolecularFormula Mo, MolecularWeight 95.95)",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/23932",
      "kind": "database",
      "license": "PubChem public database"
    },
    "pubchem-si": {
      "title": "PubChem compound CID 5461123, silicon (MolecularFormula Si, MolecularWeight 28.085)",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5461123",
      "kind": "database",
      "license": "PubChem public database"
    },
    "usgs-mcs2026-molybdenum": {
      "title": "USGS Mineral Commodity Summaries 2026, Molybdenum",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf",
      "kind": "report",
      "license": "US government work, public domain"
    },
    "usgs-mcs2026-silicon": {
      "title": "USGS Mineral Commodity Summaries 2026, Silicon",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf",
      "kind": "report",
      "license": "US government work, public domain"
    },
    "usgs-critical-2025": {
      "title": "About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)",
      "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals",
      "kind": "web",
      "license": "public domain (USGS)"
    },
    "ec-crm": {
      "title": "Critical raw materials (European Commission, list under Regulation (EU) 2024/1252)",
      "url": "https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en",
      "kind": "web",
      "license": "European Commission web page"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/molybdenum-disilicide/"
}