Tham khảo tài liệu 'friction and lubrication in mechanical design episode 2 part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Surface Coating 455 from the process a high degree of equipment reliability and low production and maintenance costs. Production chambers can handle a working diameter of 360 mm and a working height of up to 900 mm. These units have microprocessor-based automated control systems. This enables composition and a sequence of layers. For example a coating which consists of a sequence of 10 layers can be produced fully automatically in one cycle. At the present CVD is primarily used to coat machine tools with TiN. The process starts by placing parts in a chamber and heating to 1000 C. In a few hours the parts reach a uniform temperature. Gaseous chemicals are introduced into the chamber at atmospheric pressure. Chemical reactions of gaseous material produce the coating material and gaseous byproducts. Coating material crystallizes on the substrate surface. This process takes several hours and is very sensitive to process parameters. However thick coatings can be applied by this method. Physical Vapor Deposition This process relies on ion bombardment as the driving force. Temperatures are typically in the range 500-900 F for the deposition of tool coatings. This lower temperature is generally given as the major distinction between CVD and PVD processes. The following are the major PVD coating processes 1. Sputter ion plating 2. Electron gun beam evaporation ion plating 3. Arc evaporation ion bond Sputter Ion Plating Sputter ion plating SIP takes place in a vacuum chamber containing argon at a certain known pressure. Parts to be coated are loaded into a standard fixture. The inside surface of the SIP unit as well as all of the exposed surfaces are lined with a sheet of titanium. The titanium acts as a source material. The parts are held at a positive voltage 900V with respect to titanium resulting in a glow discharge plasma generated between the workload and the titanium. The ionized argon bombards the titanium sputtering titanium atoms. These highly energized .
