Welcome to General Ruby & Sapphire

"If you want wear parts, optics, electronic parts, and jewel bearings that are totally dependable, get them from a dependable company, General Ruby & Sapphire Co."

The very reason you turn to sapphire is to provide performance in critical applications. That the sapphire you buy be properly developed, machined, and polished according to the highest standards is therefore of extreme importance. For example, in ultraprecision applications you might require tolerances to .000020". At General Ruby & Sapphire our customers can be sure that the quality of sapphire will meet the quality demands of sapphire will meet the quality demands of their products. Our years of experience enable us to help with our customer's design problems, engineering problems, and application problems, to create products that deliver results.

• Fast Off-Shelf Delivery on Most Items
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• Sapphire & Ruby Rounds & Rectangles
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• Sapphire & Ruby Balls
• 
• Sapphire Windows
• 
• Jewel Bearings
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• Electronic Insulators for Electron Tube, Spectrometer and Nuclear Applications
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• Substrates for IC and IR
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• Wear Parts
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• Sapphire & Ruby, Rods & Tubes
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• Pure Scrap for Evaporation
• 
• Orifices

Applications

Optical Applications of Sapphire Infrared:

The outstanding applications for synthetic sapphire have been as components in near infra-red equipment where sapphire has found use in systems involving lead selenide and indium antimonide detectors because of the "match" between transmission of sapphire and sensitivity of the detector material. Flat and curved windows are used in detector cells because of transmission, low cost and ease of sealing to glasses such as Corning 7520.

Lenses are also made of sapphire in place of windows in detector cells where the same properties including the intermediate refractive index of sapphire apply. IR domes made of sapphire offer the important advantages of high resistance to thermal shock, abrasive and other difficult environmental conditions.

Sapphire is an excellent substrate for filters and reticles because of its transmissivity, chemical stability, ability to take deposits well, and very high strength (allowing for extremely thin sections where needed). In many cases, sapphire has become the commonly used material (compared to others with parallel properties) because of comparitively low cost.

Lamp Envelopes:

Sapphire has found use as a lamp envelope in discharge lamps because of its excellent transmission in UV and near infra-red regions coupled with its extreme chemical stability which prevents it from breaking down under high temperature and strong radition conditions.

Light Pipes:

Sapphire rods act as an excellent IR light pipe under high temperature conditions.

Pressure Windows:

High strength chemical resistance make sapphire extremely useful as windows in high pressure applications such as combustion chamber or undersea work.

Lasers:

Sapphire doped with chromium (pink sapphire or ruby) emits monochromatic light under proper excitation conditions.

Jewel Bearings:

A variety of several hundred types and sizes of bearings made from sapphire, ruby and tungsten carbide (also spinel and agate on request) are available in the following forms:
  Vee Jewels
  Orifice Jewels
  Cup Jewels
  Endstones
  Hole jewels with straight or rounded hole, bombe surfaces or cups.

Holes sizes from .003" up to 1/4" available. Tolerances held as close as .000020" for ultra-precise needs.

Jewel bearings are available mounted in metal holders with or without threads-manufactured from brass, stainless steel, aluminum, or titanium.

See our standards list of commonly made jewel bearings to guide you in your prototype designs.

Wear Surfaces:

Highly polished sapphire, ruby or tungsten carbide shapes such as polished round and square plates. Used as a camera film and magnetic tape guides. Extreme resistance to wear and dimensional stability and relative low cost find a variety of applications in instrumentation, tooling, sales checkouts, etc.

Balls:

Precision balls from .005" to 3/4" diameter in sapphire, ruby and tungsten carbide-highly polished.

Pivots & Stylii:

For instrument pivots and scribing tools.

Electronic Components:

Polished or unpolished forms such as rods, plates, drilled tubes, threaded coil forms made from sapphire or ruby. Excellent thermal and chemical stability, low RF absorbtivity, high electrical resistivity, moderate thermal conductivity, close mechanical tolerances, no degassing problems create ideal material for difficult applications where glass or ceramics are unsuitable. Thermal coefficient of expansion can be matched to commonly available glasses and metals. Relatively low dielectric constant makes it very useful for highly stable RF capacitors and IC substrates.

 

Sapphire Properties

Sapphire is an anistrophic crystal, hexagonal system, composed of unicrystalline alpha aluminum oxide, essentially 100% pure. Various properties are a function of crystallographic direction (related to the optic axis of the crystal). In the tables below, if no orientation is shown, this indicates that the property listed does not vary appreciably in relation to orientation or the variation is less than the experimental error of measurement.

Transmission:

Transmission of synthetic sapphire is shown in the following curve. Data in UV region is approximate, as transmission depends on surface finish, internal quality and purity of individual specimen. The following curve shows transmission of sapphire uncorrected for Fresnel losses.

Young's Modulus:

50 to 55,000,000 PSI

Bending Modulus (Minimum):

20C 60,000 PSI
500C 40,000 PSI
1000C 60,000 PSI

Thermal Conductivity:

12K (-261C) = 8.0 cal/cm²/sec/C/cm
300K (23C) = .09 cal/cm²/sec/C/cm
50C = .07 cal/cm²/sec/C/cm

Coefficient of Expansion:

(Mean between 20C and T) per C

	Perpendicular to C-axis	Parallel to C-axis
50C	.0000050	.0000067
500C	.0000077	.0000083
1000C	.0000083	.0000090

Loss Tangent:

.0002 at 10¹⁰ cycles

Density:

3.98

Hardness:

Moh 9, Knoop 1525 to 2000

Chemical Resistance:

Inert to virtually all reagents at room temperatures and many at high temperatures. Essentially inert to all acids including HF, and resistant to alkalis but becoming soluble at higher temperatures.

Coefficient of Friction:

0.15 with highly polished high carbon steels (with or without lubricants)

Sealing Characteristics:

Sapphire can be wetted by glass, titanium, zirconium or moly-manganese mixtures. It can be matched to titanium, molybdenium, the high nickel-iron allows such as Carpenter 49, Kovar and the Corning glass 7520. With the good technique, bonds can be made directly to Corning 7052.

As can be seen from the list of properties, sapphire is unique when compared to optical materials useful within its transmission range in that it is by far the strongest, toughest, thermal shock and chemically resistant material available, and it can be used at far higher temperatures than most optical materials. Also, its thermal conductivity is relatively high despite its extreme electrical non-conductivity. Moderate refractive index, transparency in visible region, good transmission and relatively low emission at high temperatures plus unusual stability combine to make it valuable as a component on military optics.

 

Ruby Properties

Ruby is available in two discrete chromium dopant levels, 0.03% and 0.05% by weight substitution of Cr2O3 for Al2O3. The most common is 0.05%. Lasers operating at or near threshold power take advantage of the lower threshold and better slope efficiency of the 0.03% material in this narrow region.

Applications

• High - power Q - switched systems, capable of creating the energy densities needed to generate Thomson scattering in plasma diagnostics.
• High - brightness holographic camera systems with long coherent length.
• High - power systems useful for frequency doubling into the UV spectrum.
• Laser metal working systems capable of drilling holes in hard materials.
• Medical laser systems used for cosmetic dermatology and tattoo removal.

Physical and Optical Properties

Density		3.98 g/cc		Refractive index at 700 nm	1.7638 Ordinary Ray
Melting Point		2040° C			1.7556 Extraordinary Ray
Young's Modulus		345 Gpa		Birefringence	0.008
MOR		425 MPa		Refractive Index vs. Chromium Concentration	3 x 10-3 (Δn / % Cr2O3)
Compressive Strength		2.0 Gpa		Fluorescent Lifetime at 0.05% Cr2O3	3 ms at 300 K
Hardness		9 Mhos, 2000 Knoop		Fluorescent Linewidth (R1)	5.0 Å at 300K
Thermal Expansion	20° to 50° C	5.8 x 10-6 / ° C		Output Wavelength (R1)	6.94.3 nm
	20° to 200° C	7.7 x 10-6 / ° C		Major Pump Bands	404 nm and 554 nm
Thermal Conductivity	at 0° C	46.02 W / (m•K)
	at 100° C	25.10 W / (m•K)
	at 400° C	12.55 W / (m•K)	All values are for 60° orientation material

Quartz Properties

Quartz -- a type of vitreous, or silica glass -- exhibits a number of unique properties. These properties make quartz ideally suited for applications where high purity is required or the use temperature is high. Very few materials can match the energy transmission of quartz, especially in the ultra-violet and infrared ranges.

Germanium Properties

Germanium and germanium oxide are transparent to the infrared and are used in infrared spectroscopes and other optical equipment, including extremely sensitive infrared detectors.

The high index of refraction and dispersion properties of its oxide's have made germanium useful as a component of wide-angle camera lenses and microscope objectives. Germanium oxide is added to glass to increase the index of refraction; such glass is used in wide-angle lenses and in infrared devices. Numerous alloys containing germanium have been prepared. High purity germanium single crystal detectors can precisely identify radiation sources (e.g. for airport security).

Mixture of silicon dioxide and germanium dioxide ("silica-germania") is used as an optical material for optical fibers and optical waveguides. Controlling the ratio of the elements allows precise control of refractive index. Silica-germania glasses have lower viscosity and higher refractive index than pure silica. Germania replaced titania as the silica dopant for silica fiber, eliminating the need for subsequent heat treatment which made the fibers brittle.

Fluorides - Calcium, Barium, Magnesium

CaFl
Formula weight	78.07 amu
Melting point	1675 K (1402 °C)
Boiling point	2770 K (2500 °C)
Density	3.18 ×103 kg/m3 (solid)
Solubility	virtually none in water

BaFL
Density and phase	4.893 g.cm-3, solid
Solubility in water	1.7 g/kg (26°C)
Melting point	1368 °C
Boiling point	2260 °C
Magnetic Susceptibility	-5.1e-005 cm3/mol
Crystal structure	cubic

 

Magnesium fluoride
Density	3.148 g/cm3
Solubility (water)	0.076 g/l
Melting point	1263 °C
Boiling point	2227 °C

Silicon

Single crystal silicon is aniostropic. The crystalline directions of interest include the <100>, the <110>, and the <111> crystal directions. Material properties in these crystalline directions can be calculated from basic crystal properties, and results of this analysis are shown in Appendix A. To simplify the initial design process I assume that the silicon crystal can be considered isotropic. Following the example of Spiering et al I choose a Young's Modulus of 150GPa, and a Poisson's ratio of 0.17 for all calculations. It is the opinion of these authors that these isotropic values best reflect the aniostropic behavior of silicon in the <100> plane.

Young's Modulus	150 GPa
Poisson's Ratio	0.17
Density	2330 kg/m3

Thermal expansion coefficient of silicon.

Temperature (K)	100	200	400	1000
Linear Coefficient of Thermal Expansion (10-6/K)	-0.5	1.1	2.7	4.7

Fracture Strength of Silicon

Since silicon used is single crystal it is assumed for all intents and purposes that the material does not yield until fracture occurs. I assume that the design failure stress should be the fracture strength of silicon. The fracture strength of silicon is given by Petersen as being 7000 MPa. This extremely high failure stress is contradicted by experience with anisotropically etched diaphragms where failures stresses are estimated to be in the order of 300 MPa. Sooriakumar tracked this discrepancy to the sharp corners introduced by aniostropic etching. Analysis of his data shows stress concentration factors of up to 33 at the sharp corners in aniostropically etched specimens. Rounding of the corners by isotropic etching reduced stress concentration and increased failure load for the specimens.

It is assumed in this design process that the fracture stress of silicon is 7000 MPa, with stress concentration factors of 33 possible at sharp corners produced by aniostropic etching.

Fracture Toughness

Silicon is a brittle material. Failure usually occurs along <111> cleavage planes. Analysis of failure in silicon can be helped by the use of fracture mechanics models. Using these models requires knowing the fracture toughness for the materials involved.

K_1c fracture toughness values are given for different crystal directions

Silicon Direction	K1c (MPa m1/2 )
<111>	0.83 to 0.95
<100>	0.91
<110>	0.94
Polycrystalline Silicon	0.94

• Spiering, V.L., Bouwstra, S., Spiering, R., On chip decoupling zone for package-stress reduction. Sensors and Actuators, A.39, 1993, 149-156.
• Petersen, K.E., Silicon as a mechanical material, Proc. IEEE., Vol. 70, No. 5, 1982
• Sooriakumar, Chan, Savage and Fugate, A comparative study of wet vs. dry isotropic etch to strengthen silicon micro-machined pressure sensor, Electrochemical Soc. Proc., Vol. 95-27.
• Ericson, F, et al., Hardness and fracture toughness of semiconducting materials studied by indentation and erosion techniques, Materials Science and Engineering, A 105/106 (1988) pp 131-141