Zircon C728
Grade · default condition
C728 = dense sintered zircon porcelain
Choose for gas-tight, high-strength electrical/thermal ceramic parts: insulators, nozzles, thermocouple sheaths, foundry tooling.
Values for the C728 condition
Other Zircon tempers and conditions
Zircon is listed in 4 conditions; see the grade overview at Zircon.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Bonded zircon refractory brick / shape | Choose for glass-tank paving, ladle and slide-gate refractories where slag/glass corrosion resistance matters more than strength. | — | — | — | 900 HV | 3 W/m·K |
Fused-cast / electrofused zircon | Choose for glass-furnace throat and paver blocks or high-grade refractory grain where maximum density and glass-corrosion resistance are required. | — | — | — | 1,100 HV | 4 W/m·K |
C728DefaultThis page Dense sintered zircon porcelain | Choose for gas-tight, high-strength electrical/thermal ceramic parts: insulators, nozzles, thermocouple sheaths, foundry tooling. | — | — | — | 1,150 HV | 5 W/m·K |
Zircon sand / milled zircon flour | Choose as raw material: ceramic-glaze opacifier, investment-casting facecoat and foundry sand, or feedstock for zirconia production. | — | — | 0 | 1,200 HV | 5 W/m·K |
What is Zircon C728?
Zircon C728 is Zircon in the C728 grade — choose for gas-tight, high-strength electrical/thermal ceramic parts: insulators, nozzles, thermocouple sheaths, foundry tooling. Zircon C728 has a tensile strength of 80 MPa (11.6 ksi), weaker than 53% of ceramic grades. The elastic modulus is 190 GPa (27.6 Msi). Zircon C728 has a density of 3.7 g/cm³ (0.134 lb/in³), lighter than 63% of ceramic grades. It melts at 1,687°C (3,069 °F).
Advantages
- Low embodied carbon — 3 kg CO₂/kg, better than 88% of ceramic grades
- High service temperature — 1,500°C (2,732 °F), better than 80% of ceramic grades
- Good corrosion resistance — 88/100, better than 77% of ceramic grades
Zircon C728 properties
Typical room-temperature values for Zircon C728; 11 are specific to this condition. Other listed values are Zircon reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical4
Zircon C728 has a density of 3.7 g/cm³ (0.134 lb/in³), lighter than 63% of ceramic grades. It melts at 1,687°C (3,069 °F).
Mechanical11
Zircon C728 has a tensile strength of 80 MPa (11.6 ksi), weaker than 53% of ceramic grades. The elastic modulus is 190 GPa (27.6 Msi).
Thermal5
Zircon C728 is rated for continuous service to 1,500°C (2,732 °F). It conducts heat at 4.5 W/m·K (2.6 BTU/hr·ft·°F), worse than 64% of ceramic grades. Thermal expansion is 4.2 µm/m·K (2.33 µin/in·°F).
Electrical5
Zircon C728 is an electrical insulator with a dielectric strength of 12 kV/mm (304.8 V/mil) and a resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (88/100), better than 77% of ceramic grades.
Sustainability4
Producing a kilogram of Zircon C728 takes about 40 MJ of energy and emits 3 kg of CO₂ — less than 88% of ceramic grades. Typical recycled content is 3%.
Manufacturability3
Zircon C728's machinability is not recommended (5/100, worse than 59% of ceramic grades).
Common Calculations4
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Zircon C728
Is Zircon easy to machine?
Green or bisque bodies machine easily with carbide tooling; after firing only diamond grinding, lapping and ultrasonic/laser machining are practical.
Can Zircon be welded?
Not weldable — join by ceramic-to-metal brazing (Mo-Mn metallizing), glass frit sealing or high-temperature cements.
Can Zircon be formed, bent or molded?
Formed by dry pressing, isostatic pressing, slip casting or extrusion of milled zircon flour with clay/binder, then fired at 1500–1700 °C; allow ~12–18 % firing shrinkage.
What surface finishes work on Zircon?
Diamond grind and polish for sealing faces; glazing improves surface sealing and thermal-shock-crack resistance; no plating or anodizing applies.
Zircon 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 |
|---|---|---|
| ZrO2ZrO2+HfO2 basis; stoichiometric ZrSiO4 = 67.2 % ZrO2 | 64 – 67.2 | 66 |
| HfO2naturally substitutes for Zr; usually reported inside ZrO2 | 0.8 – 1.8 | 1.2 |
| TiO2impurity from rutile | ≤ 0.2 | 0.08 |
| Fe2O3impurity | ≤ 0.15 | 0.05 |
| Al2O3impurity / bond phase | ≤ 0.6 | 0.25 |
| U+Th (trace)natural radionuclides — relevant to NORM handling rules | ≤ 0.05 | 0.02 |
| SiO2stoichiometric 32.8 % | ≥ 31.5 (balance) | — |
Zircon C728 — frequently asked
What is Zircon C728 used for?
Zircon C728 is typically used for foundry sand/refractories, ceramic glaze opacifier, kiln furniture, investment casting shell and raw material for ZrO2 production. In short: low-expansion refractory silicate; 1500 °C service capability; feedstock for zirconia.
What is the tensile strength of Zircon C728?
Zircon C728 has a typical tensile strength of 80 MPa (11.6 ksi) — weaker than 53% of ceramic grades. Strength varies by condition: see the 4 listed tempers.
Is Zircon C728 easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 59% of ceramic grades). Green or bisque bodies machine easily with carbide tooling; after firing only diamond grinding, lapping and ultrasonic/laser machining are practical.
Can Zircon C728 be welded?
Not weldable — join by ceramic-to-metal brazing (Mo-Mn metallizing), glass frit sealing or high-temperature cements.
What surface finishes work on Zircon C728?
Diamond grind and polish for sealing faces; glazing improves surface sealing and thermal-shock-crack resistance; no plating or anodizing applies.
Can Zircon C728 be formed, bent or molded?
Formed by dry pressing, isostatic pressing, slip casting or extrusion of milled zircon flour with clay/binder, then fired at 1500–1700 °C; allow ~12–18 % firing shrinkage.
What is the maximum service temperature of Zircon C728?
Zircon C728 is rated for continuous use to about 1,500°C (2,732 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ANSI/ASTM C728 — Standard Specification for Zircon Porcelain (technical ceramic classification) — ASTM International (2019)
- ASM Engineered Materials Handbook, Vol. 4: Ceramics and Glasses — ASM International (1991)
- Handbook of Refractory Practice / Refractories Handbook (zircon and zircon-bonded products) — Harbison-Walker / CRC (2005)
- GB/T 21114 — X (used for zircon assay); GB/T industry grades — SAC (2019)
- Technical zircon ceramic and fused-cast zircon datasheets — CoorsTek / Saint-Gobain / Iluka Resources (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.