Carbide interlayer

Figure 9. Schematic diagram showing the proposed nucleation mechanism diamond nuclei form on a carbide interlayer on a carbide-forming refractory metal substrateJ Initially, carburization consumes all available C to form a carbide surface layer. A minimum C surface concentration required for diamond nucleation cannot be reached on the substrate surface. With increasing carbide layer thickness, the C transport rate stows and the C surface concentration increases. When the C surface concentration reaches a critical level for diamond nucleation, or a surface C cluster attains a critical size, a diamond nucleus forms. (Reproduced with permission.)...

Advanced fiber reinforced ceramic composite (FRC) having self-healing function has been developed to be suitable for the turbine blades of jet engine. The composite includes the silicon carbide interlayer as healing agent at the interface between alumina fiber bundle and alumina... 

Zhou, X. G., Yu, H. J., Huang, B. Y. (2007). Effect of Silicon Carbide Interlayers on the Mechanical Behavior of T800-HB-Fiber-Reinforced Silicon Carbide-Matrix Composites. Key Engineering Materials, 368-372,1844-1846. doi 10.4028/www. scientific.net/KEM.368-372.1844. 

Sintered cutting tips or inserts containing c-BN can be brazed to a cemented carbide or other substrates. Brazing bond strength is increased by interlayers of various carbides, nitrides, or carbonitrides [268],... 

Coating life in moist atmospheres is also influenced by the effects of moisture on the substrate-coating interface, and marked improvements in life have been claimed by the use of moisture-protective pre-treatments of the substrate. Niederhauser et al ° studied a wide range of metals and titanium nitride, titanium carbide and chromium carbide as pre-treatments. The material was sputter-deposited on a steel substrate, and then sulphided by introducing hydrogen sulphide into the sputtering chamber in order to improve molybdenum disulphide adhesion. They found a marked improvement in life, particularly with a rhodium or palladium interlayer, but the actual degree of improvement is confused because they also used co-sputtered PTFE, and this is discussed further in Section 10.6. 

Subsequent preliminary comparative studies of the behavior of an SiC based layer on Ta, Mo, Ti and steel substrates showed that better mechanical stability was obtained with a coating deposited on tantalum. This element was consequently considered to make PFCVD deposit/interlayer/steel stacks. Tantalum can be produced by physical vapor deposition (PVD), at variable thickness, with reproducible morphology. Note that preparation by chemical vapor deposition with or without plasma assistance (CVD or PECVD) is possible at low temperature but would require an optimization study in order to be compatible with the deposition conditions of the silicon carbide layer, the aim being to increase the mechanical stability. 

The SHS/DPIC of diamond- gradually dispersed TiB2/Si cermets was performed. In case of fixing diamond in cermet matrix, there are two methods. One is the physical fixing just like a diamond ring, and the other is the chemical fixing by covalent bond between diamond and metal in the cermet. In this work, we studied the latter system and considered that a metal carbide is very suitable as an interlayer to form the covalent bond.. There are many metals in periodic table to form the metal carbide. However, the... 

Over the last four decades there have been a number of attempts to wed the unique benefits of polyurethane adhesives with the benefits of other adhesive systems. These attempts have led to the reporting of a variety of urethane hybrids. Early work focused on simple blends for example, in 1964 Union Carbide blended organic isocyanates with ethylene-vinyl acetate copolymers [66]. These blends were used as an adhesive interlayer in glass laminations, particularly safety glass laminates. Similarly, polylurethane poxy blends for safety glass laminates were reported in 1970 [67]. 

Luthra, K.L., M.K. Bran, and G.S. Corman. 1994. Protective coatings with reactive interlayer on reinforcement in silicon carbide composite. U.S. PATENT 5,294,489, 1994 March 15. 

As introduced above, the reaction of boron carbide with metal carbides can be used to fabricate metal borides or metal boride/boron carbide composites in a controlled way during densification if boron carbide or free boron is used in excess, or if carbon is bonded by another additive. Although the incompatibility of B4C and metal carbides is well known, many attempts have been undertaken to produce composites or coatings thereof but failed as soon as equilibrium conditions were approached. Physical or chemical vapor deposition of B4C on hard metal substrates, or WC coatings on boron carbides are typical problems (e.g., [252]). In both cases, interlayers of graphite form and hence result in an unsatisfactory adhesion of the deposited coating to the substrate. 

Fig. 4 CBN coating on a cemented carbide substrate with interlayers to increase coating adhesitm (Source Uhlmann et al. 2009)...

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