Ferro-Ceramic Grinding Inc. machines over 15 different materials
Sapphire
Even those who don’t know a thing about sapphire machining have heard of sapphire as a material. Not only is it considered a precious gemstone, but it’s also a form of the common aluminum oxide material.
One of the unique properties of the sapphire is that it’s a single crystal form, which means it has no grain boundaries or porosity. Sapphire machining presents a special manufacturing challenge because it takes grounding and possibly polishing to obtain the most useful size and tolerance.
The hardness, stiffness, and transparency of sapphire material properties make them useful in many industrial components, such as analytical equipment and even aerospace windows. Sapphires are especially prevalent in the consumer sector because of its transparent face material.
Sapphire Properties
There are numerous advantages to using sapphire as a design material. Sapphire has an extremely high use temperature, hardness, optical clarity, flexural strength, and chemical resistance that make it an increasingly popular choice. Applications for sapphire material include grocery store scanner windows, watch glasses, and countless semiconductor and aerospace/military applications.
Learn more about sapphire machining and properties by getting in touch with our helpful staff at Ferro-Ceramic.
| Properties | Units | Test | Value |
|---|---|---|---|
| Physical | |||
| Chemical Formula | - | - | a-Al2O3 |
| Density, r | g/cm3 | ASTM C20 | 3.97 |
| Color | - | - | white/ transparent |
| Crystal Structure | - | - | trigonal |
| Water Absorption | % @R.T. | ASTM C373 | 0.0 |
| Hardness | Moh's | - | 9 |
| Hardness | knoop (kg/mm2) | Knoop 100g | 2200 |
| Mechanical | |||
| Compressive Strength | MPa @ R.T. | ASTM C773 | 2000 |
| Tensile Strength | MPa @ R.T. | ACMA Test #4 | 250 - 400 |
| Modulus of Elasticity (Young's Mod.) | GPa | ASTM C848 | 250 - 400 |
| Flexural Strength (MOR) | MPa @ R.T. | ASTM F417 | 760 - 1035 |
| Poisson's Ratio, u | - | ASTM C818 | 0.29 |
| Fracture Toughness, KIc | MPa x m1/2 | Notched Beam Test | 1.89 |
| Thermal | |||
| Max. Use Temperature (* denotes inert atm.) | ºC | No load cond. | ~2000 |
| Thermal Shock Resistance | DT (ºC) | Quenching | 200 |
| Thermal Conductivity | W/m-K @ R.T. | ASTM C408 | 40 |
| Coefficient of Linear Thermal Expansion, al | mm/m-ºC (~25ºC through ±1000ºC) | ASTM C372 | 7.9 - 8.8 |
| Specific Heat, cp | cal/g-ºC @ R.T. | ASTM C351 | 0.18 |
| Electrical | |||
| Dielectric Constant | 1MHz @ R.T. | ASTM D150 | 9.3 - 11.4 |
| Dielectric Strength | kV/mm | ASTM D116 | 15 - 50 |
| Electrical Resistivity | Wcm @ R.T. | ASTM D1829 | 1017 |