spore: profile
id: max-phases
spore_version: 0.2
family: carbide-nitride-boride-ceramics
name: MAX phase ceramics
abbreviation: MAX
role: layered machinable ceramic-metal hybrid for furnace heating elements, sliding parts and machinable high-temperature parts
category: ceramics
type: carbides
summary: |
  MAX phases are layered hexagonal carbides and nitrides with the general formula Mn+1AXn. Titanium silicon carbide, Ti3SiC2, is the best-studied member. Bulk Ti3SiC2 is stiff and machinable, and it conducts heat and electricity like a metal. The 1997 review gives 43 W/m K for its thermal conductivity. A Kanthal grade sold as Maxthal 312 measured about 4.47 g/cm3 with about 1 % porosity. Ti2AlC values in this file are calculated (DFT) and the Ti3AlC2 values are heat-capacity fits. Oxidation data for Ti2AlC and Ti3AlC2 were not read, so they are not given.
best_for: Electric heating elements that run hot in vacuum or inert gas, and machinable bulk parts (patent US6903313B2; Barsoum and El-Raghy 1997)
weakest_at: Oxidation in air above about 1100 to 1200 degC (patent), and decomposition into TiC above about 1400 degC in vacuum (Pang et al. 2009)
identity:
  formula: Ti3SiC2, a layered ternary carbide of the Mn+1AXn family (n = 2, A = Si, X = C)
  crystal_system: hexagonal
  space_group: P63/mmc
  source: shef-magnus2020
  where: 'Section 1 (Introduction): Ti3SiC2 crystallizes in the space group P63/mmc. The hexagonal structure is stated in drexel-prog312 abstract (layered structure, hexagonal)'
  designations:
    - system: Trade name
      code: Maxthal 312
      source: shef-magnus2020
      where: 'Section 3.2: prealloyed Maxthal 312 powder, X-ray diffraction of the as-received powder'
tags:
  environments: []
  stresses:
    - extreme-heat
  applications:
    - thermal-control
    - mechanisms
    - structures
properties:
  - benchmark: density
    label: Density, Maxthal 312 Ti3SiC2 bar (Kanthal grade)
    value: 4.47
    unit: g/cm3
    scope: material
    conditions:
      grade: Maxthal Ti3SiC2 bar, 15 mm diameter, made by Kanthal's proprietary method
      porosity: about 1 %
      phases: samples A and B contain TiC and TiSi2 impurities
    method: Density as printed by the authors with a tilde (approximately); measured on the sample
    status: ground
    source: ansto-pang2009
    where: Experimental, Sample Preparation (first paragraph)
  - benchmark: vickers_hardness
    label: Vickers hardness, Ti3SiC2 family (class range)
    value: 4
    value_high: 6
    bound: range
    unit: GPa
    scope: material
    conditions:
      basis: range the review gives for the 312 ternary carbides as a class (Ti3SiC2, Ti3GeC2 and Ti3AlC2), not one measured sample
      load: not stated
    method: Class range stated in the review abstract; the review calls these ternaries relatively low in hardness
    status: ground
    source: drexel-prog312
    where: Abstract, first sentences
  - benchmark: vickers_hardness
    label: Vickers hardness, bulk Ti3SiC2 hot pressed from TiCx and Si
    value: 6
    unit: GPa
    scope: material
    conditions:
      form: bulk Ti3SiC2 hot pressed from TiCx (x = 0.67) and Si at 1300 to 1500 degC in argon
      note: hardness falls as the indentation load rises
    method: Vickers hardness as stated in the record abstract ('about 6 GPa')
    status: ground
    source: kist-hwang2005
    where: Abstract, sentence on Vickers hardness
  - benchmark: vickers_hardness
    label: Vickers hardness, spark-plasma-sintered Maxthal 312 disc (composite)
    value: 5.8
    unit: GPa
    scope: material
    conditions:
      form: SPS disc from Maxthal 312 powder at 99 % relative density; composite of 51.8 wt% Ti3SiC2, 36.4 wt% TiC and 11.8 wt% TiSi2
      load: 19.6 N for 15 s
    method: Vickers microhardness measured on the polished disc; the paper gives 4 GPa for the intrinsic hardness of monolithic Ti3SiC2 for comparison
    status: ground
    source: shef-magnus2020
    where: Section 3.2 (phase analysis, relative density) and Section 3.6 (Vickers-induced deformation)
  - benchmark: thermal_conductivity
    value: 43
    unit: W/m K
    scope: material
    conditions:
      basis: stated for Ti3SiC2 in the review abstract; temperature not given
    method: Value stated in the review abstract
    status: ground
    source: drexel-prog312
    where: Abstract, sentence on thermal conduction
  - benchmark: yield_strength
    label: Yield point, polycrystalline 312 ternaries at 1300 degC
    value: 100
    unit: MPa
    scope: material
    conditions:
      temperature: 1300 degC
      form: polycrystalline 312 ternary carbide (class value)
    method: Yield point stated in the review abstract, described as quite high for that temperature
    status: ground
    source: drexel-prog312
    where: Abstract, sentence on plastic deformation above 1200 degC
  - benchmark: max_service_temp
    label: Upper temperature limit in vacuum or inert gas
    value: 2300
    unit: degC
    scope: material
    conditions:
      atmosphere: vacuum, inert or reducing atmosphere
      basis: practical limit set in the patent because Ti3SiC2 breaks down into TiCx and Si at 2330 degC
    method: Limit stated in the patent description; a design statement, not a measured service test
    status: ground
    source: us6903313
    where: Description, paragraph on the decomposition temperature
  - benchmark: max_service_temp
    label: Upper temperature limit in air (oxidizing atmosphere)
    value: 1100
    value_high: 1200
    bound: range
    unit: degC
    scope: material
    conditions:
      atmosphere: oxidizing atmospheres such as air
    method: Range stated in the patent description; design statement
    status: ground
    source: us6903313
    where: Description, paragraph on oxidizing atmospheres
  - benchmark: density
    label: Calculated crystal density, Ti2AlC (x = 0)
    value: 3.997
    unit: g/cm3
    scope: material
    conditions:
      basis: calculated crystal density of the x = 0 end member, this study
    method: DFT calculation; density from the calculated lattice constants (Table 5). Not measured
    status: calculated
    source: arxiv-2005-08604
    where: Table 5, row x = 0.00, rho column
  - benchmark: bulk_modulus
    label: Calculated bulk modulus, Ti2AlC (x = 0)
    value: 135
    unit: GPa
    scope: material
    conditions:
      basis: DFT elastic constants averaged to a polycrystal, this study (x = 0)
      pressure: 0 GPa
    method: Calculated from the elastic constants in Table 2 (this study). Not measured
    status: calculated
    source: arxiv-2005-08604
    where: Table 2, row x = 0.00 (This study), B column
  - benchmark: shear_modulus
    label: Calculated shear modulus, Ti2AlC (x = 0)
    value: 113
    unit: GPa
    scope: material
    conditions:
      basis: DFT elastic constants averaged to a polycrystal, this study (x = 0)
    method: Calculated from the elastic constants in Table 2 (this study). Not measured
    status: calculated
    source: arxiv-2005-08604
    where: Table 2, row x = 0.00 (This study), G column
  - benchmark: elastic_modulus
    label: Calculated Young's modulus, Ti2AlC (x = 0)
    value: 265
    unit: GPa
    scope: material
    conditions:
      basis: DFT elastic constants averaged to a polycrystal, this study (x = 0)
    method: Calculated from the elastic constants in Table 2 (this study). Not measured
    status: calculated
    source: arxiv-2005-08604
    where: Table 2, row x = 0.00 (This study), Y column
  - benchmark: debye_temperature
    label: Calculated Debye temperature, Ti2AlC (x = 0)
    value: 723
    unit: K
    scope: material
    conditions:
      basis: from the calculated average sound velocity, x = 0
    method: Anderson method from DFT elastic constants (Table 5). Calculated, not measured
    status: calculated
    source: arxiv-2005-08604
    where: Table 5, row x = 0.00, Debye temperature column
  - benchmark: melting_point
    label: Calculated melting temperature, Ti2AlC (x = 0)
    value: 1663
    unit: K
    scope: material
    conditions:
      basis: calculated melting temperature of the x = 0 end member
    method: Calculated by the DFT paper (Table 5, Tm column). Not a measured melting point
    status: calculated
    source: arxiv-2005-08604
    where: Table 5, row x = 0.00, Tm column
  - benchmark: debye_temperature
    label: Debye temperature from low-temperature heat capacity, Ti3AlC2
    value: 484.2
    unit: K
    scope: material
    conditions:
      basis: Ti3AlC2 hot-pressed bulk (x = 0 of Ti3Al1-xSixC2), linear fit of Cp/T against T squared below 7 K
      method_fit: low-temperature Debye law
    method: Approximated Debye temperature from the authors' specific-heat fit (Table 3). The fit is representative per the paper
    status: ground
    source: mdpi-ti3alc2-2021
    where: Table 3, Ti3AlC2 row, Debye temperature column
  - benchmark: sommerfeld_coefficient
    label: Sommerfeld coefficient, Ti3AlC2
    value: 4.848
    unit: mJ mol-1 K-2
    scope: material
    conditions:
      basis: electronic specific-heat coefficient from the same low-temperature fit, Ti3AlC2 bulk (x = 0)
    method: Read from the authors' specific-heat fit (Table 3)
    status: ground
    source: mdpi-ti3alc2-2021
    where: Table 3, Ti3AlC2 row, gamma column
corrosion:
  - environment: Air at about 1000 degC, oxidation of bulk Ti3SiC2
    headline: Good oxidation resistance at 1000 degC, with a parabolic rate constant that the review prints
    effect: The 1997 review calls Ti3SiC2 highly oxidation resistant and prints a parabolic rate constant at 1000 degC in kg2 m-4 s-1 (not converted here). The patent says it resists oxidation considerably better than Ta, Mo, W and graphite, but gives no test data. It describes very good oxidation properties in air up to 1100 to 1200 degC, with a surface oxide of TiO2. The rating low is the assistant's judgement from these statements.
    rating: low
    conditions:
      atmosphere: air
      temperature: 1000 degC for the rate; up to 1100 to 1200 degC (patent)
    source: drexel-prog312
    where: Abstract (oxidation resistance); patent us6903313 description, oxidizing atmosphere paragraph
  - environment: Vacuum annealing, 1400 to 1550 degC, Maxthal Ti3SiC2 with TiC and TiSi2
    headline: Above 1400 degC in vacuum, Ti3SiC2 starts to decompose into TiC
    effect: TiC reacts with TiSi2 between 1400 and 1450 degC to form Ti3SiC2. Above 1400 degC, Ti3SiC2 decomposes into TiC, and the rate rises with temperature and dwell time (in-situ neutron diffraction). The patent gives a decomposition temperature of 2330 degC, where Ti3SiC2 breaks down into TiCx and Si. The rating moderate is the assistant's judgement from the onset temperature.
    rating: moderate
    conditions:
      atmosphere: vacuum
      temperature: 1400 to 1550 degC
      sample: Maxthal Ti3SiC2 bulk with TiC and TiSi2 impurities
    source: ansto-pang2009
    where: Abstract; Results, phase fraction against dwell time (Samples A and B)
risks:
  hazards:
    - text: 'Vendor safety statements for titanium silicon carbide (samaterials.com product page): H315, H319, H351 and H335, with the signal word Warning. The same page says its data are based on theoretical values and are for reference only. No manufacturer safety data sheet was read.'
      ghs:
        - H315
        - H319
        - H351
        - H335
      source: samaterials-ti3sic2
      where: Product page, hazard statement line; read as a page text
  failure_risks:
    - mode: Oxidation of the carbide in air
      trigger: Heating in air above about 1100 to 1200 degC
      consequence: The surface oxidizes to TiO2 and the Ti3SiC2 phase is lost near the surface (patent description).
      severity: moderate
      source: us6903313
      where: Description, oxidizing atmosphere paragraph
    - mode: Decomposition into TiC
      trigger: Vacuum annealing above about 1400 degC
      consequence: Ti3SiC2 decomposes into TiC and silicon is lost; the rate increases with temperature and dwell time.
      severity: moderate
      source: ansto-pang2009
      where: Abstract; Results, decomposition rates for Samples A and B
    - mode: Impurity phases in commercial powder
      trigger: Use of the Maxthal 312 grade with TiC and TiSi2 present
      consequence: Impurity phases change the decomposition behaviour; the sample with more Ti3SiC2 decomposed less in the test.
      severity: low
      source: ansto-pang2009
      where: Results, comparison of phase abundance, Samples A and B
  side_effects: []
  handling: []
  mitigations:
    - text: Use the element in vacuum, inert or reducing gas above about 1100 to 1200 degC. The patent says the heating element is intended for vacuum, inert and reducing atmospheres up to 2300 degC.
      source: us6903313
      where: Description, use in vacuum, inert and reducing atmospheres
uses:
  - application: thermal-control
    device: Electrical resistance heating elements for furnaces (Ti3SiC2 wire or element)
    example: A US patent describes a heating element of Ti3SiC2 for heat treatment and sintering in inert or reducing gas, in oxidizing atmospheres or in vacuum, up to extremely high temperatures such as 2300 degC. The 2020 Sheffield paper also lists furnace tubes, high-temperature burner nozzles and electric furnace elements as current uses.
    source: us6903313
    where: Description, intended use paragraph; background of shef-magnus2020 (Section 1)
  - application: mechanisms
    device: Bearings and other sliding parts (candidate use)
    example: The 2020 Sheffield paper says the layered nature and self-lubricating properties of MAX phases make them a candidate for bearings and other sliding applications. This is a candidate use, not a flight or field result.
    source: shef-magnus2020
    where: Section 1 (Introduction), paragraph on applications
  - application: structures
    device: Machinable bulk parts
    example: The 1997 review says these 312 ternaries are as readily machinable as graphite and are not susceptible to thermal shock.
    source: drexel-prog312
    where: Abstract, sentence on machinability and thermal shock
supply:
  - subject: Titanium
    abundance: 5,650 ppm in the Earth's crust (USGS PP 1802-A, Table A1)
    producers:
      - country: China
        share_percent: 70.3
        year: 2025
      - country: Japan
        share_percent: 14.3
        year: 2025
      - country: Russia
        share_percent: 6.8
        year: 2025
      - country: Kazakhstan
        share_percent: 4.3
        year: 2025
      - country: Saudi Arabia
        share_percent: 3.2
        year: 2025
    critical_lists: []
    recycling: Not stated in the USGS titanium sections read for this profile.
    substitutes: []
    source: usgs-mcs2026-titanium
    where: 'World Sponge Metal Production table, 2025 column (world total 370,000 t, shares calculated by Space Mushroom); Import Sources (2021-24) line. Abundance: USGS PP 1802-A, Table A1, Ti row'
  - subject: Aluminium (used in Ti3AlC2 and Ti2AlC)
    producers:
      - country: China
        share_percent: 60.8
        year: 2025
      - country: India
        share_percent: 5.7
        year: 2025
      - country: Russia
        share_percent: 5.3
        year: 2025
      - country: Canada
        share_percent: 4.5
        year: 2025
    critical_lists: []
    recycling: 'USGS 2026: about 3.6 million tons of aluminum was recovered from purchased scrap in the United States in 2025.'
    substitutes: []
    source: usgs-mcs2026-aluminum
    where: World Smelter Production table, 2025e column (world total 74,000 as printed; shares calculated by Space Mushroom); Recycling paragraph
media: []
documents:
  - title: Barsoum and El-Raghy, A Progress Report on Ti3SiC2, Ti3GeC2 and the H-phases, M2BX, J. Materials Synthesis and Processing 5, 197-216 (1997)
    type: paper
    url: https://research.coe.drexel.edu/mse/layeredsolids/wp-content/uploads/2011/01/Prog_rep_312.htm
    year: 1997
  - title: Hwang, Park and Kim, Mechanical properties of synthesized Ti3SiC2 by hot pressing from TiCx/Si powder mixture, KIST repository record (Key Engineering Materials 287, 2005)
    type: paper
    url: https://pubs.kist.re.kr/handle/201004/136659
    year: 2005
  - title: Magnus et al., Synthesis and microstructural evolution in ternary metalloceramic Ti3SiC2 consolidated via the Maxthal 312 powder route, Ceramics International 46 (2020) 15342-15356
    type: paper
    url: https://sheffield.ac.uk/media/29142/download
    year: 2020
  - title: Pang et al., Effect of Vacuum Annealing on the Thermal Stability of Ti3SiC2/TiC/TiSi2 Composites, Journal of the Australian Ceramic Society 45(1), 72-77 (2009)
    type: paper
    url: https://apo.ansto.gov.au/bitstreams/aeb3b687-f63e-76a5-e053-150a9d89ded9/download
    year: 2009
  - title: Structure, Morphology, Heat Capacity, and Electrical Transport Properties of Ti3(Al,Si)C2 Materials, Materials 14(12), 3222 (2021), open access
    type: paper
    url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8230697/
    year: 2021
  - title: 'Recently synthesized (Ti1-xMox)2AlC (0 < x < 0.20) solid solutions: DFT study of structure, mechanics and thermodynamics (arXiv 2005.08604)'
    type: paper
    url: https://arxiv.org/pdf/2005.08604
    year: 2020
  - title: US patent US6903313B2, Resistance heating element for extreme temperatures
    type: report
    url: https://patents.google.com/patent/US6903313B2/en
  - title: Wikipedia, MAX phases (composition, structure and history only)
    type: database
    url: https://en.wikipedia.org/wiki/MAX_phases
  - title: 'Vendor product page, titanium silicon carbide Ti3SiC2 (samaterials.com): hazard statements and density'
    type: datasheet
    url: https://samaterials.com/cm6197-titanium-silicon-carbide-ti3sic2.html
  - title: USGS Mineral Commodity Summaries 2026, Titanium and Titanium Dioxide
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
    year: 2026
  - title: USGS Mineral Commodity Summaries 2026, Aluminum
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
  - title: USGS Professional Paper 1802-A, Table A1 crustal abundances
    type: report
    url: https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf
    year: 2017
gaps:
  - Titanium borocarbide, named in the brief as a MAX phase, has no source read in this run, so it is not covered here.
  - 'Ti2AlC and Ti3AlC2 oxidation: the open papers were blocked or unreadable (RSC, Taylor and Francis, HAL, NSF PAR, Curtin). Only search snippets were seen, so no oxidation value is used for them.'
  - Measured density, hardness and elastic moduli of Ti2AlC and Ti3AlC2 were not read from a fetched page. The Ti2AlC values in this file are DFT results only.
  - Measured Young's modulus (283 GPa) and fracture toughness of Ti3SiC2 from Gao et al. 1998 (Springer) could not be opened, so they are not used.
  - Electrical conductivity of Ti3SiC2 (1997 review) is printed with a garbled unit symbol, so it is not used. Thermal conductivity and thermal expansion of Ti2AlC and Ti3AlC2 were not read.
  - Ti2AlC thermal expansion (8.2 x 10-6 K-1) appears in the DFT paper introduction, citing another work. It was not converted, so it is not used.
  - Debye temperature, Sommerfeld coefficient and vickers_hardness are not canonical names in property-canon.yaml. They are used as snake_case names and noted here.
  - 'No CAS number: the vendor page that prints it could not be opened, so cas is left out.'
  - 'Designations: no fetched source printed a UNS, EN, DIN or JIS code for Ti3SiC2. Only the trade name Maxthal 312 is listed.'
  - 'Hazard data: one vendor page only, which says its values are theoretical. A second vendor''s search snippet gives a different signal word and codes; it was not read. No manufacturer safety data sheet was read, so handling is empty.'
  - Silicon supply (production and critical-list status) and aluminium crustal abundance were not read in this run. The titanium critical-minerals listing could not be confirmed (USGS critical-minerals page blocked), so critical_lists is empty.
  - 'Environments: no source read supports a space environment tag, so tags.environments is empty. Radiation tolerance is mentioned in the Sheffield introduction with references that were not read.'
  - Synthesis route of the commercial grade is proprietary (Kanthal), per the ANSTO paper. No production route for pure Ti3SiC2 was read.
sources:
  drexel-prog312:
    title: Barsoum and El-Raghy, A Progress Report on Ti3SiC2, Ti3GeC2 and the H-phases, M2BX, J. Materials Synthesis and Processing 5, 197-216 (1997)
    url: https://research.coe.drexel.edu/mse/layeredsolids/wp-content/uploads/2011/01/Prog_rep_312.htm
    kind: paper
    license: Drexel University web copy, cited not reproduced
  kist-hwang2005:
    title: Hwang, Park and Kim, Mechanical properties of synthesized Ti3SiC2 by hot pressing from TiCx/Si powder mixture (Key Engineering Materials 287, 2005; DOI 10.4028/www.scientific.net/KEM.287.194)
    url: https://pubs.kist.re.kr/handle/201004/136659
    kind: paper
    license: KIST repository record, cited not reproduced
  shef-magnus2020:
    title: Magnus et al., Synthesis and microstructural evolution in ternary metalloceramic Ti3SiC2 consolidated via the Maxthal 312 powder route, Ceramics International 46 (2020) 15342-15356
    url: https://sheffield.ac.uk/media/29142/download
    kind: paper
    license: Accepted author copy hosted by the University of Sheffield, cited not reproduced
  ansto-pang2009:
    title: Pang et al., Effect of Vacuum Annealing on the Thermal Stability of Ti3SiC2/TiC/TiSi2 Composites, Journal of the Australian Ceramic Society 45(1), 72-77 (2009)
    url: https://apo.ansto.gov.au/bitstreams/aeb3b687-f63e-76a5-e053-150a9d89ded9/download
    kind: paper
    license: ANSTO repository, cited not reproduced
  mdpi-ti3alc2-2021:
    title: Structure, Morphology, Heat Capacity, and Electrical Transport Properties of Ti3(Al,Si)C2 Materials, Materials 14(12), 3222 (2021)
    url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8230697/
    kind: paper
    license: CC BY 4.0 (open access)
  arxiv-2005-08604:
    title: 'Recently synthesized (Ti1-xMox)2AlC (0 < x < 0.20) solid solutions: deciphering the structural, electronic, mechanical and thermodynamic properties via ab initio simulations (arXiv 2005.08604)'
    url: https://arxiv.org/pdf/2005.08604
    kind: paper
    license: arXiv preprint, cited not reproduced
  us6903313:
    title: US patent US6903313B2, Resistance heating element for extreme temperatures
    url: https://patents.google.com/patent/US6903313B2/en
    kind: web
    license: patent document, cited not reproduced
  wiki-max-phases:
    title: Wikipedia, MAX phases (used for composition, structure and history only)
    url: https://en.wikipedia.org/wiki/MAX_phases
    kind: web
    license: CC BY-SA 4.0
  samaterials-ti3sic2:
    title: Vendor product page, titanium silicon carbide (Ti3SiC2), samaterials.com (hazard statements; values marked theoretical)
    url: https://samaterials.com/cm6197-titanium-silicon-carbide-ti3sic2.html
    kind: datasheet
    license: vendor product page, cited not reproduced
  usgs-mcs2026-titanium:
    title: USGS Mineral Commodity Summaries 2026, Titanium and Titanium Dioxide
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-aluminum:
    title: USGS Mineral Commodity Summaries 2026, Aluminum
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    kind: report
    license: public domain (USGS)
  usgs-pp1802a:
    title: USGS Professional Paper 1802-A, Critical Mineral Resources of the United States, Table A1 (crustal abundances)
    url: https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf
    kind: report
    license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 16
  unreachable: 6
  caveats: 8
  note: 'Written in this run from pages read in this run: the Barsoum and El-Raghy 1997 review (Drexel), the KIST 2005 record, the Magnus et al. 2020 Sheffield PDF, the Pang et al. 2009 ANSTO PDF, the Materials 2021 open-access paper (PMC8230697), the arXiv 2005.08604 DFT paper, the US6903313 patent, Wikipedia (composition and history only), the samaterials.com product page (read by WebFetch), and the USGS titanium, aluminum and PP 1802-A documents. Unreachable: Springer (Gao 1998), RSC, Taylor and Francis (Tallman 2013), MDPI landing pages, American Elements (bot check), HAL, NSF PAR, Curtin and the USGS critical-minerals page.'
story:
  recipe:
    line: MAX phases have the general formula Mn+1AXn. M is an early transition metal, A is an A-group element and X is carbon or nitrogen (Wikipedia, composition only). Ti3SiC2 has titanium as M, silicon as A and carbon as X, with n = 2 (Magnus et al. 2020). Bulk Ti3SiC2 is made by hot pressing or spark-plasma sintering, from TiCx and Si powders (Hwang et al. 2005) or from the commercial Maxthal 312 powder (Magnus et al. 2020; Pang et al. 2009).
    parts:
      - name: Titanium
        symbol: Ti
        role: The early transition metal M of the Mn+1AXn formula. Three titanium per formula unit.
      - name: Silicon
        symbol: Si
        role: The A-group element. It is the layer that leaves the structure when Ti3SiC2 decomposes (the patent gives TiCx and Si as the breakdown products).
      - name: Carbon
        symbol: C
        role: The X element, two carbon per formula unit, forming the carbide layers with titanium.
  risk_groups:
    - title: For people
      level: 0
      verdict: Only vendor hazard codes; no SDS read
      lead: The only hazard statements here come from one vendor product page. They include a suspected-carcinogen code (H351) and irritant codes, and the vendor says its values are theoretical. Read the manufacturer's safety data sheet before handling the powder.
      points:
        - label: Hazard codes
          line: The vendor lists H315, H319, H351 and H335 with the signal word Warning. A second vendor's search result gave different codes; that listing was not read.
        - label: Powder
          line: No dust, ignition or inhalation statement for Ti3SiC2 was read. Keep the powder controlled until a safety data sheet is read.
    - title: If a part overheats
      lead: These limits come from the patent and from the 2009 vacuum-annealing study.
      points:
        - label: In air
          line: The patent describes use in oxidizing atmospheres up to 1100 to 1200 degC. Above this, the surface oxidizes to TiO2.
        - label: In vacuum
          line: In vacuum annealing above 1400 degC, Ti3SiC2 starts to decompose into TiC, and faster at higher temperature or longer dwell.
  why: MAX phases combine metal-like and ceramic-like behaviour. The 2009 ANSTO paper describes Ti3SiC2 as thermally shock resistant, thermally and electrically conductive, damage tolerant, lightweight, highly oxidation resistant, elastically stiff and mechanically machinable. The 1997 review gives a thermal conductivity of 43 W/m K for Ti3SiC2 and calls the 312 family as readily machinable as graphite. Ti3SiC2 is the most stable ternary in the Ti-Si-C system, and like the other MAX phases it does not melt but decomposes into its binary phases (Magnus et al. 2020).
  uses:
    - where: Furnace heating elements
      line: A US patent describes a Ti3SiC2 heating element for heat treatment and sintering in inert or reducing gas, in oxidizing atmospheres such as air, or in vacuum, up to 2300 degC. The 2020 Sheffield paper lists furnace tubes, burner nozzles and electric furnace elements as current uses.
    - where: Bearings and sliding parts
      line: The 2020 Sheffield paper says the layered structure and self-lubricating properties make MAX phases a candidate for bearings and other sliding applications. This is a candidate use with no test result given here.
    - where: Machinable bulk parts
      line: The 1997 review says these 312 ternaries machine as readily as graphite and are not susceptible to thermal shock.
  can_do:
    - label: Stiffness, calculated
      benchmark: elastic_modulus
      line: A DFT study gives a calculated Young's modulus of 265 GPa for Ti2AlC (x = 0). It is calculated, not measured, and it is the only stiffness value in this file.
    - label: Hardness
      benchmark: vickers_hardness
      line: Bulk Ti3SiC2 hot pressed from TiCx and Si measured about 6 GPa (Hwang et al. 2005). A Maxthal-based composite measured 5.8 GPa (Magnus et al. 2020). The 1997 review gives a class range of 4 to 6 GPa.
    - label: Upper temperature
      benchmark: max_service_temp
      line: The patent gives 1100 to 1200 degC in air and 2300 degC in vacuum or inert gas. These are design statements, not service tests.
  compare: 'Ti3SiC2 measured in this file is denser than the calculated Ti2AlC: 4.47 g/cm3 for the Kanthal grade against 3.997 g/cm3 calculated for Ti2AlC. Thermal conductivity of 43 W/m K is measured for Ti3SiC2 in the review; no Ti2AlC conductivity is read. The Ti2AlC values are DFT results and should not be compared directly with the measured Ti3SiC2 values.'
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Hardness
      benchmark: vickers_hardness
  handling:
    - Keep heating-element service in air below about 1100 to 1200 degC (patent).
    - Commercial grades carry TiC and TiSi2. In vacuum above about 1400 degC they can decompose further (Pang et al. 2009).
    - No safety data sheet was read, so no powder handling rule is sourced here.
  good_for:
    - Furnace heating elements in vacuum or inert gas. The patent claims use up to 2300 degC.
    - Machinable, damage-tolerant bulk parts. The 1997 review calls the 312 family as machinable as graphite.
  watch_out:
    - Oxidation in air above about 1100 to 1200 degC, with the surface converting to TiO2 (patent).
    - Commercial powder carries TiC and TiSi2 impurities at several percent, which changes its decomposition behaviour (Pang et al. 2009).
    - 'Hazard data are thin: one vendor page, and no manufacturer safety data sheet was read.'
  verdict: Ti3SiC2 is a stiff, machinable carbide. Its best-sourced values are a Kanthal-grade density of 4.47 g/cm3, a thermal conductivity of 43 W/m K, and heating-element use up to 2300 degC in vacuum, with air use limited to about 1100 to 1200 degC. The Ti2AlC values are calculated, the Ti3AlC2 values are heat-capacity fits, and titanium borocarbide is not covered.