Aluminum nitride hardness

Table 3 summarizes the properties of the so-called nonmetallic hard materials, including diamond and the diamondlike carbides B C, SiC, and Be2C. Also iacluded ia this category are comadum, AI2O2, cubic boroa nitride, BN, aluminum nitride, AIN, siUcon nitride, Si N, and siUcon boride, SiB (12). 

Numerous ceramics are deposited via chemical vapor deposition. Oxide, carbide, nitride, and boride films can all be produced from gas phase precursors. This section gives details on the production-scale reactions for materials that are widely produced. In addition, a survey of the latest research including novel precursors and chemical reactions is provided. The discussion begins with the mature technologies of silicon dioxide, aluminum oxide, and silicon nitride CVD. Then the focus turns to the deposition of thin films having characteristics that are attractive for future applications in microelectronics, micromachinery, and hard coatings for tools and parts. These materials include aluminum nitride, boron nitride, titanium nitride, titanium dioxide, silicon carbide, and mixed-metal oxides such as those of the perovskite structure and those used as high To superconductors. 

A comparison of critical temperature differences of resins filled with several ceramic particulates is shown in Figure 4. The volume fraction of all these composites is 34.2%. The critical temperature difference of epoxy filled with hard particulates was classified into three groups on the basis of thermal shock resistance. Composites filled with a strong particulate, such as silicon nitride or silicon carbide, showed high thermal shock resistance. Some improvement in thermal shock resistance was recognized for silica-filled composites. Composites filled with alumina or aluminum nitride showed almost comparable or lower resistance compared with the neat resin. 

Aluminum nitride EINECS 246-140-8. Used as a semiconductor in electronics, nitriding of steel steel manufacture. Crystals mp 2150-2200° hardness 9 to 10 on Moh s scale. Atomergic Chemetals Carborundum Corp. Mandoval Ltd Sigma-Aldrich Fine Chem. 

Another main group element nitride with considerable hardness is aluminum nitride, AIN. It is important as a ceramic insulator with high thermal conductivity. It has the hexagonal wurtzite type structure (h-ZnS) [111]. In contrast to the high-pressure compound c-BN, it is prepared by various methods at ambient pressure [22,112]. 

Among non-oxide ceramics, aluminum nitride developed recently. Its mechanical properties (hardness, breaking strength) are modest, bnt its thermal conductivity is very high. This conductivity associated with high electrical resistance, good dielectric property and a coefficient of expansion close to that of silicon, which varies linearly with the temperature, make it an excellent material for substrates for power micro-electronics (Figure 7.12). 

Nitrides are compounds of nitrogen where nitrogen has a formal oxidation state of -3. Nitride ceramics have been widely used as cutting materials, hard coatings, insulators, etc. Among the group of carbides, silicon nitride (SijN ) is the most widely studied and industrially applied ceramic material, followed by aluminum nitride (AIN) and boron nitride (BN). 

The nitrides reviewed here are those which are commonly produced by CVD. They are similar in many respects to the carbides reviewed in Ch. 9. They are hard and wear-resistant and have high melting points and good chemical resistance. They include several of the refractory-metal (interstitial) nitrides and three covalent nitrides those of aluminum, boron, and silicon. Most are important industrial materials and have a number of major applications in cutting and grinding tools, wear surfaces, semiconductors, and others. Their development is proceeding at a rapid pace and CVD is a major factor in their growth. 

The nitrides AIN, GaN and InN are known. Only aluminum reacts directly with nitrogen. GaN is obtained on reaction of Ga or Ga203 at 600-1000° with NH3 and InN by pyrolysis of (NH4)3InF6. All have a wurtzite structure (Fig. 2-3). They are fairly hard and stable, as might be expected from their close structural relationship to diamond and the diamond-like BN. 

---