Seven, thermal spraying technology
Due to the bright future of surface technology, in the past few years, the output value of thermal spray technology has increased by 7% to 10%, and the output value of the European market in 2000 was about 950 million euros. As confirmed by a large number of exhibitors at international trade fairs, not only oxy-fuel flames, arcs, plasma arcs and high-speed oxy-fuel flame spraying, but also PTA processes, coupled with optimized control systems, continue to stand firm.
Cold gas spraying processes have also gained new applications. When cold sprayed, the material being sprayed is no longer completely melted by thermal energy, but is plasticized when the particles impact the base material at high speed. New research by erosion of flying objects shows that the opposite effect is that at a particular particle velocity, strongly accelerated particles have a very viscous effect as opposed to removal, and dense coatings or structures are formed only by being sprayed. The kinetic energy of the material is produced.
Thermal spraying not only sprays metal, but also sprays a mixture of plastic and ceramics. The range of metals that can be processed ranges from low melting point zinc to high melting point titanium and tantalum. In addition to the traditional anti-corrosion protection and wear-resistant applications, the new process also carries out special tasks in electrical engineering, mechanical engineering and equipment engineering. For example, coatings sprayed with copper not only have high density and hardness, but also achieve about 90% conductivity of pure copper (IACS standard).
The temperature and mass flow of the thermally sprayed particles have a decisive influence on the deposition rate, cooling and solidification of the coating. For this reason, measuring the particles in flight is the basic method for checking the bond strength, microstructure and porosity of the coating.
If the rolls used in the paper and textile industry are made of aluminum instead of steel, they must be sufficiently resistant to wear, corrosion and mechanical and thermal stress. The functional coating (base material AlMg5) made by thermal spraying was placed on a special test bench, applying mechanical and thermal loads. The coating most suitable for this application was confirmed to be a buffer coating system consisting of NiCr80/90 and WC-Co88/12, sprayed by high velocity oxy-fuel flame.
In use, the new turbine can operate at temperatures above 1 000 °C. The working life of the coated parts is mainly determined by the structural stability of the thermal insulating coating. The structural stability can be improved by plasma arc spraying of the zirconia coating, and partial stabilization can be achieved by using yttrium oxide.
The traditional method of making cast iron cylinder sleeves is cast during the manufacture of an aluminum alloy cylinder crankcase in accordance with a die casting process. Since these cast iron sleeves have a certain wall thickness, this will create a large distance between the shaft holes of each cylinder, resulting in an oversized engine and an excessive weight if it is appropriate at the shaft hole of the cylinder. Lining can eliminate these shortcomings. To this end, Volkswagen AG and Sulzer-Metco have developed the “Rotating Plasma Arc Spraying Processâ€, which uses a 10 000 °C hot plasma arc spray technique to spray a composite of steel and molybdenum onto the cylinder wall.
The literature describes the advances in thermal spray nanocrystalline ceramic coatings; in addition, a new thermal spray consulting system (SpriWar.) is introduced to introduce users to how to select spray consumables, process variables, torch powder composition and Spray parameters, etc.
Due to the bright future of surface technology, in the past few years, the output value of thermal spray technology has increased by 7% to 10%, and the output value of the European market in 2000 was about 950 million euros. As confirmed by a large number of exhibitors at international trade fairs, not only oxy-fuel flames, arcs, plasma arcs and high-speed oxy-fuel flame spraying, but also PTA processes, coupled with optimized control systems, continue to stand firm.
Cold gas spraying processes have also gained new applications. When cold sprayed, the material being sprayed is no longer completely melted by thermal energy, but is plasticized when the particles impact the base material at high speed. New research by erosion of flying objects shows that the opposite effect is that at a particular particle velocity, strongly accelerated particles have a very viscous effect as opposed to removal, and dense coatings or structures are formed only by being sprayed. The kinetic energy of the material is produced.
Thermal spraying not only sprays metal, but also sprays a mixture of plastic and ceramics. The range of metals that can be processed ranges from low melting point zinc to high melting point titanium and tantalum. In addition to the traditional anti-corrosion protection and wear-resistant applications, the new process also carries out special tasks in electrical engineering, mechanical engineering and equipment engineering. For example, coatings sprayed with copper not only have high density and hardness, but also achieve about 90% conductivity of pure copper (IACS standard).
The temperature and mass flow of the thermally sprayed particles have a decisive influence on the deposition rate, cooling and solidification of the coating. For this reason, measuring the particles in flight is the basic method for checking the bond strength, microstructure and porosity of the coating.
If the rolls used in the paper and textile industry are made of aluminum instead of steel, they must be sufficiently resistant to wear, corrosion and mechanical and thermal stress. The functional coating (base material AlMg5) made by thermal spraying was placed on a special test bench, applying mechanical and thermal loads. The coating most suitable for this application was confirmed to be a buffer coating system consisting of NiCr80/90 and WC-Co88/12, sprayed by high velocity oxy-fuel flame.
In use, the new turbine can operate at temperatures above 1 000 °C. The working life of the coated parts is mainly determined by the structural stability of the thermal insulating coating. The structural stability can be improved by plasma arc spraying of the zirconia coating, and partial stabilization can be achieved by using yttrium oxide.
The traditional method of making cast iron cylinder sleeves is cast during the manufacture of an aluminum alloy cylinder crankcase in accordance with a die casting process. Since these cast iron sleeves have a certain wall thickness, this will create a large distance between the shaft holes of each cylinder, resulting in an oversized engine and an excessive weight if it is appropriate at the shaft hole of the cylinder. Lining can eliminate these shortcomings. To this end, Volkswagen AG and Sulzer-Metco have developed the “Rotating Plasma Arc Spraying Processâ€, which uses a 10 000 °C hot plasma arc spray technique to spray a composite of steel and molybdenum onto the cylinder wall.
The literature describes the advances in thermal spray nanocrystalline ceramic coatings; in addition, a new thermal spray consulting system (SpriWar.) is introduced to introduce users to how to select spray consumables, process variables, torch powder composition and Spray parameters, etc.
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