What is the melting point of an alumina disc?

The melting point of alumina is approximately 2050°C, but this should not be treated as the service temperature of a finished disc. Usable temperature depends on alumina grade, disc geometry, mechanical load, support method, atmosphere, and thermal cycle.

How is an alumina disc different from a washer, substrate, or porous disc?

An alumina ceramic disc is a dense, flat Al₂O₃ round component used for insulation, high-temperature support, wear-resistant contact, or precision fixturing. A washer or ring is defined by its through-hole, a substrate is generally a thin electronic base, and a porous disc is designed for gas or liquid flow.

Do you supply standard-size alumina ceramic discs?

Several diameter and thickness combinations are available as current size references. Availability and shipment timing are confirmed according to the required grade, dimensions, tolerances, surface condition, and quantity.

What dimensions and features can be customized?

ADCERAX can review OD, thickness, center or patterned holes, slots, countersinks, counterbores, chamfers, edge radii, reliefs, and pockets from a drawing. Critical tolerances, flatness, parallelism, surface finish, quantity, and mating-part conditions are reviewed before quotation.

Which grade should I choose: 96%, 99%, 99.5%, or 99.7% alumina?

A 96% grade is often considered for general support, spacer, and insulation duties, while higher-purity grades may suit stricter electrical, wear, temperature, or cleanliness requirements. Final selection depends on temperature, atmosphere, load, voltage, surface condition, and the required test standard.

Can an alumina disc be used for high-voltage insulation?

Dense alumina can provide strong electrical insulation, but finished-part performance depends on grade, thickness, surface cleanliness, edge condition, creepage, clearance, temperature, surface humidity, and the test method. A dielectric or hipot pass result should not be assumed from the material name alone.

Alumina Ceramic Disc (Al2O3) for Insulation & Fixtures

An alumina ceramic disc is a dense, sintered Al₂O₃ round component that forms a rigid, non-metallic interface between mating parts. Its disc geometry supports controlled contact, separation, or load distribution and distinguishes it from porous filter media, thin electronic substrates, and washer-style rings.

Alumina Ceramic Disc Benefits

Finished-part performance depends on the selected alumina grade, disc geometry, surface condition, operating environment, and agreed inspection method.

Thermal stability: Retains structural rigidity at elevated temperatures when the load, support method, atmosphere, and thermal cycle are properly specified.
Dimensional control: Flatness, parallelism, thickness, and surface finish can be defined for controlled contact, alignment, and fixture repeatability.
Electrical isolation: Provides nonconductive separation in electrical assemblies; actual performance depends on grade, thickness, surface cleanliness, edge condition, creepage, clearance, and test method.
Surface durability: The hard ceramic surface supports repeated contact and wear-resistant positioning in fixtures and mechanical assemblies.
Cleanable contact surface: Surface finish, cleaning, handling, and packaging can be specified for applications with controlled-contamination requirements.

Alumina Ceramic Disc Properties

Property	Unit	96% Al₂O₃	99% Al₂O₃	99.5% Al₂O₃	99.6% Al₂O₃	99.7% Al₂O₃	99.8% Al₂O₃	99.9% Al₂O₃	99.99% Al₂O₃
Alumina content	%	96	99	99.5	99.6	99.7	99.8	99.9	99.99
Density	g/cm³	3.6-3.75	3.83	3.89	3.91	3.92	3.93	3.94	3.98
Color	–	white	Ivory	Ivory	Ivory	Ivory	Ivory	Ivory	Ivory
Water absorption	%	0	0	–	0	0	0	0	0
Young’s modulus (Elastic modulus)	GPa	300	350	375	356	357	358	359	362
Shear modulus	GPa	–	–	152	–	–	–	–	–
Bulk modulus	GPa	–	–	228	–	–	–	–	–
Poisson’s ratio	–	–	–	0.22	–	–	–	–	–
Compressive strength	MPa	1910	2210	2500	2552	2554	2556	2558	2570
Flexural strength	MPa	260	300	340	345	346	347	348	365
Fracture toughness	MPa·m¹ᐟ²	–	–	4	–	–	–	–	–
Hardness	GPa	14.5	17	17	23	24	25	26	30
Thermal conductivity	W/m·K	20	31	31	31-33	31-33	31-33	31-35	31-35
Thermal shock resistance ΔT	°C	–	–	–	222	223	224	225	228
Maximum use temperature (no load)	°C	1450	1680	≤1750	1755	1760	1765	1770	1800
Coefficient of thermal expansion	10⁻⁶/°C	7.6	7.6	7.6	7.6	7.5	7.5	7.4	7.4
Volume resistivity	Ω·cm	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴
Dielectric constant (relative permittivity)	–	9.2	9.5	9.8	9.83	9.84	9.85	9.86	9.92
Dielectric strength	kV/mm	15	19	16.9	23.2	23.4	23.6	23.8	24
Dissipation factor (loss factor @ 1 kHz)	–	–	–	0.0002	–	–	–	–	–

Choose an Alumina Grade by Operating Requirement Select the grade after reviewing temperature, atmosphere, mechanical load, voltage, surface condition, cleanliness, geometry, and the required test method. Purity alone does not define finished-disc performance.

Grade for Review	Typical Starting Point	Confirm Before Quotation
96% Al₂O₃	General support, spacer, and insulation duties	Temperature, voltage, load, dimensions, and flatness
99%–99.5% Al₂O₃	Higher-purity electrical, wear, or clean-contact requirements	Grade source, test method, surface condition, and environment
99.7% Al₂O₃	High-purity precision, high-temperature, or electrical review	Availability, geometry, thermal cycle, load, voltage, and cleanliness

Specifications of Alumina Ceramic Disc

Alumina Disc
Item No.	Diameter(mm)	Thick(mm)
AT-DIS001	25	1.5
AT-DIS002	32	2
AT-DIS003	38	2
AT-D-42-2	42	2
AT-DIS004	51	2
AT-DIS005	64	3
AT-DIS006	76	3
AT-D-82-6	82	6
AT-DIS007	89	4
AT-DIS008	102	4
AT-DIS009	127	5
AT-DIS010	152	5

Alumina Ceramic Discs Packaging

Each disc is dust-wiped, separated by soft interlayers, and sealed in labelled clean bags. Rigid cartons with corner protection limit edge chipping.

Alumina Ceramic Disc Applications

ADCERAX manufactures application-specific alumina ceramic discs for thermal support, electrical isolation, precision contact, and wear-resistant positioning. Product forms include solid discs, spacer discs, carrier discs, and drawing-based parts with controlled surfaces and finished edges.

Laboratory Heating & Sample Support

Ceramic Products We Make

Solid alumina support and separator discs
Flat sample carrier and cover discs
Discs with ground or polished contact surfaces
Discs with chamfered or radiused edges

Application Problems Addressed

Controlled flatness provides a stable support surface and helps prevent samples or containers from rocking.
Dense, cleanable alumina surfaces support applications where contact cleanliness and repeated use are important.
Suitable grade, thickness, and edge finishing help the ceramic disc retain its shape during repeated thermal cycles.
Finished edges help reduce chipping during handling, loading, and removal.

High-Voltage Insulating & Spacer Discs

Ceramic Products We Make

Solid electrical-insulation discs
Center-hole ceramic spacer discs
Multi-hole mounting and locating discs
Stepped discs with ground faces and finished edges

Application Problems Addressed

Dense alumina provides non-metallic separation between conductive components.
Controlled disc thickness helps maintain consistent spacing and alignment.
Ground contact faces provide stable seating between mating parts.
Smooth surfaces and finished edges help limit contamination, edge damage, and localized electrical stress.

Precision Fixturing, Lapping & Polishing

Ceramic Products We Make

Flat fixture and work-support discs
Lapping and polishing carrier discs
Wear-resistant locating and contact discs
Discs with holes, slots, pockets, steps, notches, or alignment features

Application Problems Addressed

Controlled flatness and parallelism help reduce rocking and uneven contact across the working surface.
Hard alumina contact surfaces resist wear during repeated positioning and abrasive processing.
Ground or polished faces can provide the required contact condition on one or both sides of the disc.
Integrated locating features help control part position and orientation without adding separate ceramic pieces.

Alumina Ceramic Discs Usage Instructions

Use

1. Mount discs on clean, flat support surfaces to avoid rocking and uneven loading.
2. Prevent point loading on thin discs; distribute load with smooth plates or compliant pads.
3. Always re-check clamp torque after the first heat cycle, since initial shrink-fit or bow correction can shift load balance.
4. For electrical insulation uses, verify that disc edges are free of micro-chips before assembly.
Storage

1. Keep in sealed, dry bags with desiccant packs to prevent moisture absorption that could lower dielectric strength.
2. Use interlayers (foam, soft paper, or plastic films) to prevent edge-to-edge contact.
3. Store vertically on edge racks for discs thinner than 1 mm to minimize bowing or creep.
4. Maintain storage areas below 40% relative humidity, away from corrosive vapors or vibration.
Cleaning

1. Use non-metallic tools to avoid scratching or introducing conductive particles.
2. Suitable methods: mild ultrasonic cleaning, isopropanol or ethanol wipe, or DI-water rinse with quick dry.
3. Avoid hydrofluoric acid or strong alkalis (NaOH, KOH) that chemically attack Al₂O₃.
4. After cleaning, handle discs with powder-free gloves to prevent finger oils that may cause hot spots or leakage.
Common mistakes & fixes

1. Edge chipping during handling → specify discs with chamfer or radius; handle with trays or vacuum pick-up tools.
2. Uneven heating marks → confirm required flatness grade (e.g., ≤0.1 mm/100 mm) and ensure uniform support; avoid three-point clamping that causes hot spots.
3. Electrical leakage spikes → check for surface moisture or contamination; pre-bake at 150–200 °C to remove absorbed water before hipot testing.
4. Warping of thin discs → store vertically and clamp evenly; for long cycles above 1200 °C, specify reinforced support or lower bow tolerance.
5. Surface contamination during polishing → cover discs with protective film until ready for use; request clean-room level packaging if used in sensitive assemblies.

Alumina Ceramic Discs FAQ

What is the melting point of an alumina disc?
The melting point of alumina is approximately 2050°C, but this should not be treated as the service temperature of a finished disc. Usable temperature depends on alumina grade, disc geometry, mechanical load, support method, atmosphere, and thermal cycle.
How is an alumina disc different from a washer, substrate, or porous disc?
An alumina ceramic disc is a dense, flat Al₂O₃ round component used for insulation, high-temperature support, wear-resistant contact, or precision fixturing. A washer or ring is defined by its through-hole, a substrate is generally a thin electronic base, and a porous disc is designed for gas or liquid flow.
Do you supply standard-size alumina ceramic discs?
Several diameter and thickness combinations are available as current size references. Availability and shipment timing are confirmed according to the required grade, dimensions, tolerances, surface condition, and quantity.
What dimensions and features can be customized?
ADCERAX can review OD, thickness, center or patterned holes, slots, countersinks, counterbores, chamfers, edge radii, reliefs, and pockets from a drawing. Critical tolerances, flatness, parallelism, surface finish, quantity, and mating-part conditions are reviewed before quotation.
Which grade should I choose: 96%, 99%, 99.5%, or 99.7% alumina?
A 96% grade is often considered for general support, spacer, and insulation duties, while higher-purity grades may suit stricter electrical, wear, temperature, or cleanliness requirements. Final selection depends on temperature, atmosphere, load, voltage, surface condition, and the required test standard.
Can an alumina disc be used for high-voltage insulation?
Dense alumina can provide strong electrical insulation, but finished-part performance depends on grade, thickness, surface cleanliness, edge condition, creepage, clearance, temperature, surface humidity, and the test method. A dielectric or hipot pass result should not be assumed from the material name alone.

Request an Alumina Disc Engineering Review

Send your drawing or sample information together with the operating conditions.
The more complete the input, the faster ADCERAX can review the grade, geometry, manufacturability, inspection, and packaging requirements.RFQ Checklist:

Drawing, sketch, or sample photo
Alumina grade or purity requirement
Outside diameter and thickness
Holes, slots, countersinks, counterbores, chamfers, edge radii, reliefs, or pockets
Dimensional tolerances, flatness, and parallelism
Surface finish and functional-surface requirement
Continuous and peak temperature, thermal cycle, and atmosphere
Mechanical load, support, mounting, and mating materials
Working voltage, creepage/clearance, and dielectric or hipot test requirement
Cleanliness, inspection report, labeling, and packaging needs
Prototype and production quantity

Custom Alumina Ceramic Disc Options

1. Geometry & Tolerance

Outer diameter (OD) and thickness: e.g., Ø5–Ø200 mm and 0.3–10 mm. Select OD and thickness tolerances according to the part dimensions.

Flatness and parallelism: define the required limit, measurement method, support condition, and functional surface.

Concentricity and runout can be specified for hole-to-OD or stepped features used with rotating fixtures.

For thin discs, specify the allowable bow according to the disc diameter, thickness, and support condition.

2. Machined Features

Holes and slots: specify hole diameter, pitch circle diameter (P.C.D.), quantity, countersink or counterbore dimensions, and slot geometry.

Reliefs and pockets: specify the location, profile, and depth of each recess, step, or pocket.

Alignment features: add notches or flats when orientation control is required in a jig or assembly.

3. Edges & Corners

Specify chamfers, edge radii, or other edge profiles on the drawing to support assembly and reduce chipping risk.

Define any special edge-finishing or handling requirements before quotation.

Alumina Ceramic Disc Benefits

Finished-part performance depends on the selected alumina grade, disc geometry, surface condition, operating environment, and agreed inspection method.

Thermal stability: Retains structural rigidity at elevated temperatures when the load, support method, atmosphere, and thermal cycle are properly specified.

Dimensional control: Flatness, parallelism, thickness, and surface finish can be defined for controlled contact, alignment, and fixture repeatability.

Electrical isolation: Provides nonconductive separation in electrical assemblies; actual performance depends on grade, thickness, surface cleanliness, edge condition, creepage, clearance, and test method.

Surface durability: The hard ceramic surface supports repeated contact and wear-resistant positioning in fixtures and mechanical assemblies.

Cleanable contact surface: Surface finish, cleaning, handling, and packaging can be specified for applications with controlled-contamination requirements.

Alumina Ceramic Disc Properties

Property	Unit	96% Al₂O₃	99% Al₂O₃	99.5% Al₂O₃	99.6% Al₂O₃	99.7% Al₂O₃	99.8% Al₂O₃	99.9% Al₂O₃	99.99% Al₂O₃
Alumina content	%	96	99	99.5	99.6	99.7	99.8	99.9	99.99
Density	g/cm³	3.6-3.75	3.83	3.89	3.91	3.92	3.93	3.94	3.98
Color	–	white	Ivory	Ivory	Ivory	Ivory	Ivory	Ivory	Ivory
Water absorption	%	0	0	–	0	0	0	0	0
Young’s modulus (Elastic modulus)	GPa	300	350	375	356	357	358	359	362
Shear modulus	GPa	–	–	152	–	–	–	–	–
Bulk modulus	GPa	–	–	228	–	–	–	–	–
Poisson’s ratio	–	–	–	0.22	–	–	–	–	–
Compressive strength	MPa	1910	2210	2500	2552	2554	2556	2558	2570
Flexural strength	MPa	260	300	340	345	346	347	348	365
Fracture toughness	MPa·m¹ᐟ²	–	–	4	–	–	–	–	–
Hardness	GPa	14.5	17	17	23	24	25	26	30
Thermal conductivity	W/m·K	20	31	31	31-33	31-33	31-33	31-35	31-35
Thermal shock resistance ΔT	°C	–	–	–	222	223	224	225	228
Maximum use temperature (no load)	°C	1450	1680	≤1750	1755	1760	1765	1770	1800
Coefficient of thermal expansion	10⁻⁶/°C	7.6	7.6	7.6	7.6	7.5	7.5	7.4	7.4
Volume resistivity	Ω·cm	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴	>1×10¹⁴
Dielectric constant (relative permittivity)	–	9.2	9.5	9.8	9.83	9.84	9.85	9.86	9.92
Dielectric strength	kV/mm	15	19	16.9	23.2	23.4	23.6	23.8	24
Dissipation factor (loss factor @ 1 kHz)	–	–	–	0.0002	–	–	–	–	–

Grade for Review

Typical Starting Point

Confirm Before Quotation

96% Al₂O₃

General support, spacer, and insulation duties

Temperature, voltage, load, dimensions, and flatness

99%–99.5% Al₂O₃

Higher-purity electrical, wear, or clean-contact requirements

Grade source, test method, surface condition, and environment

99.7% Al₂O₃

High-purity precision, high-temperature, or electrical review

Availability, geometry, thermal cycle, load, voltage, and cleanliness

Specifications of Alumina Ceramic Disc

Alumina Disc
Item No.	Diameter(mm)	Thick(mm)
AT-DIS001	25	1.5
AT-DIS002	32	2
AT-DIS003	38	2
AT-D-42-2	42	2
AT-DIS004	51	2
AT-DIS005	64	3
AT-DIS006	76	3
AT-D-82-6	82	6
AT-DIS007	89	4
AT-DIS008	102	4
AT-DIS009	127	5
AT-DIS010	152	5

Catalogue No.	AT-DIS001
Material	Al₂O₃
Purity	96%–99.7%
Thickness Range	0.1 mm–50 mm (±0.5–±0.25 mm tolerance)
Dimensions/Sizes	Download PDF

Alumina Ceramic Disc (Al₂O₃) for High-Temperature Insulation & Precision Fixturing

Alumina Ceramic Disc Benefits

Alumina Ceramic Disc Properties

Specifications of Alumina Ceramic Disc

Alumina Ceramic Discs Packaging