Manufacturing ceramic materials

The kinetics of solid state chemical reactions are ordinarily limited by the rate at which reactant species are able to diffuse across phase boundaries and through intervening product layers. As a result, conventional solid state techniques for manufacturing ceramic materials invariably require the use of high processing temperatures to ensure that diffusion rates are maintained at a high level, thus allowing chemical reaction to proceed without undue kinetic constraint. ... 

In this paper, we present the formation processes for ceramics from nanocrystalline fibrous PSZ powder under high pressure at different sintering temperatures. The microstructure and properties of manufactured ceramic material is studied too. 

Calcination is performed in crucibles made of platinum or related metals. Tantalum or niobium oxide can be successfully used in the manufacturing of such crucibles. Frolov et al. [505, 506] developed a method for coating various ceramic materials with tantalum or niobium oxide using an optical furnace. 

Organometallic polymer precursors offer the potential to manufacture shaped forms of advanced ceramic materials using low temperature processing. Polysilazanes, compounds containing Si-N bonds in the polymer backbone, can be used as precursors to silicon nitride containing ceramic materials. This chapter provides an overview of the general synthetic approaches to polysilazanes with particular emphasis on the synthesis of preceramic polysilazanes. 

Oligosilsesquioxanes with long-chain alkyl substituents have been offered as water-repellents and adhesives for pearlite heat-insulating plates and materials and as damping fluids and structural plasticizers for polymeric ceramic materials which allow to control the properties of the latter in the manufacture of the items concerned. 

From the time that they first appeared in Europe during the sixteenth century, Chinese porcelain objets d art were highly prized. Porcelain was far harder than any other ceramic material, and it exhibited a translucence that no European pottery could match. The first porcelain pieces to arrive in Europe inevitably found their way into the treasuries of European rulers. Then, as the porcelain trade grew, wealthy aristocrats began collecting objects made of the precious material. Europeans potters naturally looked for ways to manufacture porcelain themselves. If they discovered the secret, the profits would be immense. However, the secret of manufacturing porcelain turned out to be as elusive as the secret of the Philosopher s Stone. 

In principle these compounds offer access to materials with AliCh-SiCL and Al203 2Si02 stoichiometries. The latter stoichiometry is equivalent to the Al[OSi(OBu-t)3 (OBu-t)] precursor. The major drawbacks with these materials are their air and moisture sensitivity, and the cost of the starting materials. Although the idealized stoichiometries of the above ceramics products are not those of crystalline aluminosilicates, amorphous aluminosilicate glasses are often important in optical applications or in scratch-resistant coatings. Furthermore, they may offer potential for CVD-type applications. There still remains considerable need for simple precursors to crystalline aluminosilicates, especially for structural applications. Dense, phase pure crystalline ceramic materials are desired for optimal mechanical properties, e.g. ceramic fibers for composite manufacture. 

At about 1860 the first sterile surgical techniques were introduced by Lister. About 100 years ago, the research into the field of implants, notably of the hip joint, was started. In 1891 Znamensky first described the use of ceramic materials in the manufacture of implants. 

The manufactured 90 mm x 90 mm x 10 mm three-layered B4C/B4C-30wt%SiC tiles were tested as armor [67], The photographs of the experiment set-up of the ballistic test as well as a residual impression in the clay box that was used as one of the criteria in the ballistic performance of laminates are shown in Fig. 7.17. The ballistic penetration tests were performed to evaluate the ballistic performance of the laminates. Depth of penetration tests were used to evaluate the ballistic performance of the composite laminates. In addition, pure B4C monolithic ceramics were used as a standard for the test. Test panels were made using the three-layered B4C/B4C-SiC laminate and B4C monolithic ceramic material as the hard face. While the B4C monolithic tile had 100% of its theoretical density, the three-layered B4C/B4C-30wt%SiC laminates had about 3-4% of porosity. A commonly used Spectra fiber-reinforced polymer composite was used as backing plates. The targets were mounted on clay and the projectile was shot at the target at a specific velocity. 

Pyrometric cones (Figure 1.1) have been in common use over the past century in the manufacture of ceramic ware. They are a series of fired mixtures of ceramic materials pointing 8° from vertical, which droop after exposure to elevated temperatures for a period of time. The manufacturer [4] provides a series of sixty-four cone numbers ranging from 022 (deformation at 576°C at a heating rate of l°C/min) to 42 (over 1800°C).3 By placing a series of cones near the firing ware in a kiln, the operator can determine when firing of the ware is complete, even when the furnace temperature is only loosely controlled. The refractories industry has made cone shapes out... 

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