tailieunhanh - Handbook of Materials for Product Design Part 13

Tham khảo tài liệu 'handbook of materials for product design part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 10 Expect similar and greater equipment costs as compared to evaporative aluminum coating processes. Adequate coating coverage on complex parts may require equipment modifications. Before aluminum coating certain substrate surfaces may require wet chemical cleaning and thorough drying. Highly trained personnel are required. IVD aluminum coatings have an excellent reputation for adhesion and corrosion protection of steel. Adhesion benefits from the sputter cleaning are realized by contaminant removal high-energy creation of nucleation sites enhancing diffusion and increasing the substrate temperature. Continuing aluminum deposition results in dense and adherent structures. Sprayed Aluminum Coatings Thermal sprayed aluminum coatings have furnished manufacturing with methods that add new coating versatility for hard corrosionresistant high-temperature and abrasion-resistant coatings. Aluminum molten metal spraying is employed by arc metal spray plasma torch and detonation gun. All of these processes involve deposition by line-of-sight applications in which aluminum in powder or wire form is heated to melting and propelled by gas pressure or detonation wave onto the substrate. The angle of coating impingement is held as close as possible to 90 perpendicular to the substrate surface . The molten sprayed aluminum deposits in layers on impact forming a thick and tenaciously bonded coating see Fig. . Plasma thermal spraying has advanced the technology via the use of high-temperature electrodes which are surrounded by an inert gas that aspirates the metal powder into an ionized electrode arc between the electrodes to form a plasma. The aspirated powdered metal from the flame increases the energy of the deposition by accelerating the droplets onto the substrate surface. Plasma arc temperatures can reach 2200 to 2800 C54 and may influence the deposit and substrate properties. Effects of the plasma temperatures must be considered for the particular .