Interfacial Structure of Carbide-Coated Graphite/Al Composites and Its Effect on Thermal Conductivity and Strength

Graphite/Al composites had attracted significant attention for thermal management applications due to their excellent thermal properties. However, the improvement of thermal properties was restricted by the insufficient wettability between graphite and Al. In this study, silicon carbide and titanium carbide coatings have been uniformly coated on the graphite by the reactive sputtering method, and Graphite/Al laminate composites were fabricated by a hot isostatic pressing process to investigate the influence on thermal conductivity and mechanical properties. The results show that carbide coating can effectively improve the interfacial thermal conductance of SiC@Graphite/Al and TiC@Graphite/Al composites by 9.8 times and 3.4 times, respectively. After surface modification, the in-plane thermal conductivity (TC) of the composites with different volume fractions are all exceeding the 90% of the predictions. In comparison, SiC is more conducive to improving the thermal conductivity of composite materials, since the thermal conductivity of the 28.7 vol.% SiC@Graphite/Al reached the highest value of 499 W/m·K, while TiC is favorable for improving the mechanical properties. The finding is beneficial to the understanding of carbide coating engineering in the Graphite/Al composites.

Performance of Protective Coatings for Aluminum Alloys in the Operating Conditions of Oil Production Equipment

The paper investigates wear resistance and corrosion resistance of protective coatings of D16 aluminum alloy under conditions that simulate operation of drill pipes. The paper also presents microstructure of coatings, electrochemical potential and corrosion rate of D16 aluminum alloy with various coatings. We evaluated adhesion and wear resistance of these coatings. D16 alloy with a tungsten carbide coating has the widest range of service properties and can be used to effectively protect the surface of aluminum drill pipes during operation operation.

OXIDE FIBER COATED WITH SILICON CARBIDE FOR PRODUCING COMPOSITE MATERIALS

The article presents the results of an experiment on the application of a silicon carbide coating on an alumina fiber and studies the properties of the resulting coated fibers. The purpose of applying a barrier coating to the fibers is to protect the fiber from degradation during the manufacturing of a ceramic composite material. The paper gives the characteristics of barrier coatings, such as thickness, continuity, structure, thermal and thermo-oxidative properties. The obtained data will be useful in the development of new types of ceramic composite materials reinforced with fibers.

The Enhancement Effect of Salt Bath Chromizing for P20 Steel

The TD (Thermal Diffusion) salt bath process is used to obtain a super hard carbide coating on the material surface by utilizing the mechanism of metal thermal diffusion. In this paper, chromium carbide coating was prepared on P20 hot-pressing die steel by the TD salt bath chromizing process. Characterization of the modified surface layer was made by means of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), a micro-hardness tester and an automatic scratch tester. The influence rules of different salt bath times and temperatures on the growth thickness of the cladding layer were explored through experiments, and the optimum salt bath process scheme was determined as a temperature of 960 °C and time of 6 h. The chromium carbide coating with a thickness similar to that of chromium plating was prepared, and the average thickness of the coating was about 8–10 μm. The results showed that hardness and bonding strength of chromium carbide coating are higher than that of electroplated chromium coating. The combination of chromium carbide coating and matrix is metallurgical, while the electroplated chromium coating is physical. Immersion corrosion test results show that both coatings have good corrosion resistance in a 65% nitric acid solution.