materials
Sapphire
Sapphire is among the strongest and most robust of all optical materials, and is an optimal material for applications requiring high hardness, scratch or corrosion resistance, or high temperatures.
9.5
Relative Cost of Material
9.5
Machining Degree of Difficulty
Summary
Synthetic sapphire is a transparent optical material with exceptional strength and scratch resistance that is used in a variety of applications that require components to withstand a tough environment. As a crystalline, 100% purity version of alumina, sapphire is a challenging material that requires careful planning and strategy for machining, and is generally more costly both in terms of raw material and fabrication costs than almost any other optical material. Sapphire’s crystalline nature creates axial asymmetry in terms of its optical properties, where polishing sapphire parallel or perpendicular to its C-axis require different strategies and can increase manufacturing cost and lead time.
When dealing with advanced materials such as sapphire, it is of the utmost importance to select a qualified and experienced vendor to trust for your component manufacture. Mindrum Precision has extensive experience in sapphire, from production volume all the way down to prototypes, and our expertise allows us to achieve results that others cannot. Click here for a quote, and we will help you get your design off of the drawing board and into reality.
Applications
Since sapphire is such an advanced and durable material, it is used in many, many industries where high-stress environments are the norm. This means that sapphire is used in everything from windows and optical domes in aerospace, to prosthetics and dental applications in the medical industry, to semiconductor wafers, marine technology, scientific test crucibles, and many other applications in other industries as well. The very properties that make sapphire such a desirable material also make sapphire fabrication more costly and labor intensive, which generally necessitates more simplistic designs, but Mindrum Precision has experience with a multitude of advanced three-dimensional shapes, including everything from five-axis machining to sapphire components with internal threads.
Properties
| Material Property | Sapphire |
|---|---|
| Density (g/cm^3) | 3.97 |
| Hardness (Knoop) | 1900-2200 |
| Tensile Strength (MPa) | 400 |
| Modulus of Elasticity (GPa) | 469 |
| Flexural Strength (MPa) | 689 |
| Compressive Strength (MPa) | 2930 |
| Poisson's Ratio | .28 |
| Dielectric Strength (ac-kV/mm) | 47 |
| Dielectric Constant (@1MHz) | 9.3-11.5 |
| Volume Resistivity (ohm-cm @25°C) | 1.0E14 |
| Coefficient of Thermal Expansion (1 x 10^-6/°C) | 4.3-5.4 |
| Thermal Conductivity (W/m K) | 46 |
| Specific Heat (J/kg*K) | 669 |
| Maximum Working Temperature (°C) | 2000 |
| Index of Refraction | 1.760-1.768 |
| Birefringence (No-Ne) | .008 |
| Transmission Band Wavelength (μm) | 0.3 - 0.5 |
| *Note: Properties vary by manufacturer. The above information should be used for general reference purposes only. |
related Materials
- Alumina – Opaque, non-crystalline version of the same material with multiple purity options
- Corning ULE – Near-zero CTE materials with good optical and mechanical properties
- Fused Silica – High purity optical material with excellent mechanical properties
