Author: langfeng Time: 2017-09-26
Conventional flame spraying is the use of flammable gas combustion flame as a heat source, the spray material heated to melt and spray onto the substrate surface to form a coating. Now, for the flame spraying process, equipment development, and constantly develop a new flame spraying method. High speed oxygen fuel spraying (HVOF) is a major technical field of flame spraying. This process was developed by Union Carbide Corporation early, and in 1953 invented the oxygen-acetylene fuel D-Gun system. Followed by the use of oxygen - propane, oxygen - propylene oxide - hydrogen as fuel JetKote, TopGun, CDS, so that the technology level of this process has been continuously improved. At present, PRAXAIR company has launched JetStar high-speed air fuel spraying technology and high-speed burning wire spray gun. It uses fuels as liquid fuels such as kerosene, diesel, etc ; combustion supplies are industrial compressed air and use it to cool the gun, avoiding many HVOF guns for additional cooling requirements, reducing operating costs. The JetStar system uses 19 L / h of liquid fuel and 4 m 3 / min of compressed air at a cost of only $ 7 per hour while using oxygen-kerosene at $ 29 per hour, oxygen-acetylene at $ 38 per hour, - Hydrogen is $ 85 per hour. Another new process developed by PRAXAIR is the FlameStar Type III High Speed Combustion Wire Spray (HVCW) process using wire instead of powder. At present, the company is exploring the best uniform wire feed speed to match the high spray quality. EUTECTIC company recently with their first set of high-speed impact melting (HVIF) process system into the HVOF ranks.
The company's new TeroJet system utilizes the high pressure (about 2MP) of oxygen at the inlet to achieve sufficient combustion of the gas and high particle velocities. According to EUTECTIC company, when the slow heating of particles to 610m / s high speed, will produce a good combination of dense structure of the coating. The system is light and compact and easy to operate, just enter the oxygen pressure, air pressure and the frequency of the powder and other three parameters. The process uses kerosene as fuel, and the gun is water cooled. The TeroJet system costs less than $ 20 per hour for equipment that uses hydrogen or acetylene as fuel. According to the introduction of its spraying speed and deposition efficiency and HVOF considerable. PRAXAIR company's ultra-pole D-Gun process to produce the bonding strength of up to 210MPa. The results show that the wear resistance, corrosion resistance and micro-vibration wear performance of the coating are much higher than that of the explosive coating.
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