Al2O3 Alumina Ceramic Rings

Alumina is the most popular ceramic material resulting from nearly endless availability in different purities, starting with approx. 92 % ending up with 99.99 % qualities and the specific material characteristics. Combining a medium level bending strength with excellent wear resistance, high hardness and relatively good thermal conductivity Alumina is versatile useable. Especially in electrical applications and high temperature operations the excellent insulating behavior and dielectric strength favor Alumina for use up to 1750 °C.

Hardness is paired with high brittleness, therefore Alumina is not suited in highly loaded machinery applications. From time to time a customizing and modification in design-engineering can succeed.

Characteristics of Alumina include:

* Electrically insulating

* High thermal conductivity

* High strength and stiffness

* Available in a range of purities

* Excellent resistance to strong acids and alkalis at elevated temperatures

Applications of Alumina Ceramics

1. Plasma torch insulator

A stainless steel fabrication company needed a custom-made plasma torch, which called for a custom-made insulator with provision for cooling air flow. It had to be a precision fit in the housing, Here is the result of extrusion followed by grinding.

2. High Pressure Seal

This is a ceramic seal for a high pressure pump. The smaller component fits into the bevel in the larger ring, with the mating faces polished to a 50 nanometre Ra (N2) finish.

3. How to create a turbulent flow

Combustion is more efficient when the gases are pre-mixed. A designer of a very large burner had the problem of mixing the gases in a short path length relative to the diameter. We collaborated on the design and came up with a three-dimensional grid of tubes. The assembly is 820 mm long and 350 mm high.

4. Optical connector substrate

Tiny precision optical components can only retain their alignment if mounted on a stiff platform. In this case, meatl was not stiff enough and the thermal expansion would be too great. The solution was Macor , exploiting its excellent machinability. Note the precisely located 2.0 mm diameter through holes, and the 1.0 mm thick web in the bottom of the deepest pocket. We CNC machined this with conventional tooling.

5. Heat Shield

A research laboratory in a multinational metals company needed a structural support for some instrumentation. The support needed to carry the weight of the instruments while shielding them from radiant heat. The solution: a precision machined disc, 170 mm in diameter with view ports.

6. Corrosion Resistant Liner

These liners are used in a plasma arc furnace operating at 1600 deg. Centigrade. The liners provide protection against hydrogen chloride vapour, far outlasting any metal that was tried. The outside diameter, the length and the step are machined to a precise fit in a metal sleeve.

7. High Power Insulators

These insulators are used in a high power, high voltage, radio frequency generator. The outside diameter is precision ground. Note the delicate thickness: 3 mm! Alumina was chosen for its excellent electrical properties under extreme conditions.

Hot Ball Mill

Our client needed to react mineral samples at a temperature of 1000 deg C, with continuous aeration and tumbling. We made a ball mill shell with a capacity of 4 litres. It withstands continuous rolling with a load of 3 kg of minerals. This is an application of our special creep-resistant alumina.

Wire Guides

High purity alumina is well known as an outstandingly hard and abrasion resistant material. So, when one of Australia's largest manufacturers of wire cable came to us for a set of alumina wire guides, we were not surprised. We were surprised when they said they needed 160 guides of a completely new design custom-made in two days! Thanks to our skilled staff and excellent diamond machining, the order was shipped in 28 hours.

Frictionless clutches

A company came to us looking for a material that could be used for clutch plates. The clutch could be stationary for days between uses, so any lubricating oil would drain away. The clutch would then burn out on start-up. We suggested highly polished alumina, which can run dry with no detectable wear after very heavy sliding loads. The coefficient of friction was as low as 0.03, so there was almost no change in friction when the oil finally arrived. The clutch was a complete success - but it did require enormous springs to get the normal force high enough to transmit the torque.

Controlled Bluntness

The tips of the multiple blades of a highly specialised cutting shear had to be just fine enough to follow a soft, irregular surface, but blunt enough to be sure that they would not cut or puncture it. We came up with a precision extruded section having two concave grooves along it with controlled root radii of 0.18 and 0.16 mm. The outstanding abrasion resistance of alumina allows a perfectly formed bead to be formed on hundreds of tips.