Al2O3-99.5%
Al2O3-99.5% (ASTM C799, GB/T 3927, A995) is a high-purity alumina offering higher thermal conductivity and a finer surface finish than 96 % alumina for demanding hybrid and RF substrate work.
Reference datasheet — Al2O3-99.5% is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the A-995 condition
Al2O3-99.5% tempers and conditions
Al2O3-99.5% is supplied in 6 conditions, soft to hard. A-995 is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
82–86 % Al2O3, high glass-phase debased alumina | Cheapest alumina body for bulk insulators, bushings and low-stress wear liners where dielectric loss and thermal conductivity are not critical. | 130 | 1,000 HV | 15 W/m·K | ||
93–95 % Al2O3 | Workhorse mid-purity alumina for pump seals, valve plates, thread guides and general electrical insulation at moderate cost. | 175 | 1,200 HV | 20 W/m·K | ||
96–99 % Al2O3 substrate/technical grade | Standard thick-film/hybrid substrate and vacuum-braze alumina: good metallization compatibility and as-fired surface at lower cost than 99.5 %. | 200 | 1,350 HV | 25 W/m·K | ||
A-995Default 99.5 % Al2O3 high-purity sintered | Default high-purity grade: pick for RF/microwave and thin-film substrates, vacuum feedthroughs, laser tubes and severe wear/corrosion service. | 260 | 1,550 HV | 32 W/m·K | ||
Zirconia-toughened alumina | Use when alumina's strength and toughness are marginal — impact-loaded wear parts, mill liners, cutting/forming tools and load-bearing bio/industrial components. | 350 | 1,500 HV | 22 W/m·K | ||
Static-dissipative alumina | Choose where charge build-up must be bled off — wafer-handling end effectors, test-socket and precision-electronics tooling — accepting reduced dielectric use. | 1,400 HV | 22 W/m·K |
What is Al2O3-99.5%?
Al2O3-99.5% (ASTM C799, GB/T 3927, A995) is a high-purity alumina offering higher thermal conductivity and a finer surface finish than 96 % alumina for demanding hybrid and RF substrate work. Typical values are 3.89 g/cm3 density, 260 MPa tensile strength, 375 GPa elastic modulus, 32 W/(m.K) thermal conductivity, service to 1700 C and a 2050 C melting point, with corrosion resistance scored at 95. It is also offered in A-85, A-95, A-96, ESD and ZTA variants. The fired ceramic is brittle and rates 5 for machinability, and it costs more than Al2O3-96%, which remains the default for general thick-film substrates. Al2O3-99.5% has a density of 3.89 g/cm³ (0.141 lb/in³), lighter than 59% of ceramic grades. It melts at 2,050°C (3,722 °F). Al2O3-99.5% has a tensile strength of 260 MPa (37.7 ksi), stronger than 65% of ceramic grades. The elastic modulus is 375 GPa (54.4 Msi).
What is Al2O3-99.5% used for?
- RF/microwave substrates
- laser diode submounts
- precision hybrid circuits
Advantages
- Good corrosion resistance — 95/100, better than 97% of ceramic grades
- High service temperature — 1,700°C (3,092 °F), better than 90% of ceramic grades
- Polishes to a fine finish — 92/100, better than 89% of ceramic grades
- Low embodied carbon — 5.2 kg CO₂/kg, better than 75% of ceramic grades
Al2O3-99.5% properties
Typical room-temperature values for Al2O3-99.5%-A-995; bars are the position among ceramic grades.
Physical4
Al2O3-99.5% has a density of 3.89 g/cm³ (0.141 lb/in³), lighter than 59% of ceramic grades. It melts at 2,050°C (3,722 °F).
Mechanical12
Al2O3-99.5% has a tensile strength of 260 MPa (37.7 ksi), stronger than 65% of ceramic grades. The elastic modulus is 375 GPa (54.4 Msi).
Thermal5
Al2O3-99.5% is rated for continuous service to 1,700°C (3,092 °F). It conducts heat at 32 W/m·K (18.5 BTU/hr·ft·°F), better than 62% of ceramic grades. Thermal expansion is 8 µm/m·K (4.44 µin/in·°F).
Electrical5
Al2O3-99.5% is an electrical insulator with a dielectric strength of 18 kV/mm (457.2 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (95/100), better than 97% of ceramic grades.
Sustainability4
Producing a kilogram of Al2O3-99.5% takes about 65 MJ of energy and emits 5.2 kg of CO₂ — less than 74% of ceramic grades. Typical recycled content is 0%.
Manufacturability3
Al2O3-99.5%'s machinability is not recommended (5/100, worse than 59% of ceramic grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the ceramic family
Yield strength against density for every ceramic grade FabDigit runs. Al2O3-99.5% is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Al2O3-99.5%
Is Al2O3-99.5% easy to machine?
Machine green or bisque bodies with carbide tooling allowing ~15–20 % firing shrinkage; fired 99.5 % alumina requires diamond grinding, lapping, ultrasonic or laser machining.
Can Al2O3-99.5% be welded?
Not weldable — join by active-metal (Ti/Ag-Cu) brazing, Mo-Mn metallization plus Ni plating and brazing, glass frit sealing or ceramic adhesives.
Can Al2O3-99.5% be formed, bent or molded?
Formed by dry/isostatic pressing, extrusion, slip or injection casting and tape casting for substrates, then pressureless sintering at 1550–1750 °C (HIP for maximum density).
Al2O3-99.5% chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| SiO2residual sintering aid / glassy phase | 0 – 0.2 | 0.1 |
| MgOgrain-growth inhibitor | 0 – 0.15 | 0.07 |
| CaO | 0 – 0.1 | 0.03 |
| Na2Okept low for dielectric loss and HV insulation | 0 – 0.1 | 0.05 |
| Fe2O3 | 0 – 0.05 | 0.02 |
| Al2O3sintered polycrystalline corundum, per IEC 60672-3 C-799 / ASTM D2442 Type IV | ≥ 99.5 (balance) |
What surface finishes work on Al2O3-99.5%?
As-fired Ra ≈ 0.3–0.6 µm; lapping/polishing reaches Ra <0.05 µm for thin-film use; laser scribing, thick-film metallization, Ni/Au plating and glazing are standard.
Equivalent designations
Standards and trade names that resolve to Al2O3-99.5% in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- 99.5% Al2O3
- Similar grades
- 6474C799GB/T 3927A995
How much does Al2O3-99.5% cost?
Al2O3-99.5% is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Al2O3-99.5% — frequently asked
What is Al2O3-99.5% used for?
Al2O3-99.5% is typically used for RF/microwave substrates, laser diode submounts and precision hybrid circuits. In short: higher purity than 96 % alumina; 32 W/(m.K) thermal conductivity; thin-film surface finish.
What is the tensile strength of Al2O3-99.5%?
Al2O3-99.5% has a typical tensile strength of 260 MPa (37.7 ksi) — stronger than 65% of ceramic grades. Strength varies by condition: see the 6 listed tempers.
Is Al2O3-99.5% easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 59% of ceramic grades). Machine green or bisque bodies with carbide tooling allowing ~15–20 % firing shrinkage; fired 99.5 % alumina requires diamond grinding, lapping, ultrasonic or laser machining.
Can Al2O3-99.5% be welded?
Not weldable — join by active-metal (Ti/Ag-Cu) brazing, Mo-Mn metallization plus Ni plating and brazing, glass frit sealing or ceramic adhesives.
What surface finishes work on Al2O3-99.5%?
As-fired Ra ≈ 0.3–0.6 µm; lapping/polishing reaches Ra <0.05 µm for thin-film use; laser scribing, thick-film metallization, Ni/Au plating and glazing are standard.
Can Al2O3-99.5% be formed, bent or molded?
Formed by dry/isostatic pressing, extrusion, slip or injection casting and tape casting for substrates, then pressureless sintering at 1550–1750 °C (HIP for maximum density).
What is the maximum service temperature of Al2O3-99.5%?
Al2O3-99.5% is rated for continuous use to about 1,700°C (3,092 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Al2O3-99.5% cost?
Al2O3-99.5% is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- IEC 60672-3 Ceramic and glass insulating materials — Part 3: Specifications for individual materials (C-780/C-786/C-795/C-799) — IEC (1997)
- ASTM D2442 Standard Specification for Alumina Ceramics for Electrical and Electronic Applications — ASTM (2018)
- GB/T 3927 Test method for volume density and apparent porosity of fine ceramics / — SAC (China) (2018)
- ASM Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
- AD-96 / AD-995 alumina material properties — CoorsTek (2023)
- Fine Ceramics technical data — alumina A-473/A-479/A995, ZTA — Kyocera (2023)
- Technical alumina and ZTA property records — MatWeb / CES EduPack material data (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.