![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
Inclusions and gases in the metal have a significant influence on the strength fatigue resistance, corrosion resistance, stress corrosion cracking performance of the material. Effectively controlling the oxidation inclusions of the melt to improve the quality of the cast rod is a common goal pursued by the aluminum industry. At present, filtration and purification methods are widely used to remove inclusions in the aluminum alloy melt.
1. Formation of inclusions in aluminum alloy
Some of the inclusions in the aluminum alloy come directly from the waste, while most of it is formed during the smelting and casting process, mainly oxide inclusions. All inclusions before casting are called primary oxidation inclusions. They can be divided into two types according to their size: one is a large inclusion with uneven distribution in the macroscopic structure, which makes the alloy structure discontinuous and reduces the compactness of the casting. Become the source of corrosion and the source of cracks, thereby significantly reducing the strength and plasticity of the alloy; the other is the fine dispersion inclusions, which can not be completely removed by refining, which increases the viscosity of the melt and reduces the aluminum liquid during solidification. The ability to supplement. The secondary oxidation inclusions are mainly formed during the casting process. When pouring, the aluminum liquid is in contact with air, and oxygen and aluminum act to form oxide inclusions. The aluminum alloy is in contact with various components in the furnace gas during the smelting process to form a compound such as AL2O3. Al2O3 in the aluminum liquid increases the hydrogen content of the aluminum alloy melt. Therefore, the AL2O3 content in the aluminum liquid has a great influence on the formation of pores in the aluminum casting.
2. Filtration purification method
Foam ceramic filtration technology appeared in the 1970s, and the use of foam ceramic filter plates is the most effective way to remove inclusions in the aluminum melt. As for the metal filter and the fiber cloth filtration, only the large inclusions in the aluminum alloy melt can be removed, but the inclusions below the micron level cannot be removed, and the metal filter can also contaminate the aluminum alloy. The use of foam ceramic filter plates can filter out fine inclusions and significantly improve the mechanical properties and appearance quality of castings. It is the primary choice for the casting workshop.
3. Use and selection of filter plates
The foam ceramic filter plate is installed in a filter box between the furnace mouth and the splitter plate. The filter box is made of "Zhong Na 5" refractory material, which can pass through multiple chilling heat without cracking, and has high strength. The advantages of good thermal insulation performance are the best materials for making filter boxes and launders. The closer the filter box is to the shunt plate, the better, because it reduces the flow distance after the aluminum liquid is filtered and reduces or prevents the re-generation of oxide. The aluminum liquid flows out of the furnace through the filter box and then flows into the manifold through the flow cell. When the filter device is started, the drop before and after melt filtration is about 50mm, but as the filtration time increases, the inclusions on the surface of the filter plate and the wall of the filter wall increase, the filtration flow rate decreases, and the difference between the front and the back increases. By the end of the casting, the drop increases. Up to 60-120 mm. The filter plate must be selected according to the flow rate of the aluminum liquid. Secondly, the cleanliness of the melt, the maximum content of the inclusions and the total melt throughput should be considered. When designing the filter device, it should be ensured that the filter plate is immersed in the aluminum liquid during melt casting according to the specifications of the selected filter plate and considering the drop of the furnace mouth and the splitter plate. In addition, it must be considered that the installation and disassembly are safe and convenient, and the aluminum liquid in the filter box can be completely discharged after the melt casting. The surface of the filter plate has proven to be the most effective tool for removing oxidized inclusions in the melt. General fiber filtration can only remove large inclusions, while ceramic foam filter plates can filter out large inclusions and fine inclusions at the same time.
4. Filter principle
The ceramic foam filter plate has a multi-layer network, a multi-dimensional through hole, and a communication between the hole and the hole. During filtration, the aluminum liquid carries the inclusions along the tortuous channels and pores, and is directly intercepted, adsorbed, deposited, etc. when in contact with the foam-like skeleton of the filter plate. When the melt flows in the holes, the filter plate passage is curved, and the melt flowing through the passage changes the flow direction, in which the inclusions collide with the hole wall anvil and firmly adhere to the wall of the hole.
The main effect of the filter plate is its size and porosity to ensure that the larger the pores of the filter plate, the worse the slag removal effect. For aluminum castings with strict requirements, a filter plate with a small pore size should be selected.
Foam ceramic filter plates are currently the most effective tool for removing oxidized inclusions from the melt.
1. Formation of inclusions in aluminum alloy
Some of the inclusions in the aluminum alloy come directly from the waste, while most of it is formed during the smelting and casting process, mainly oxide inclusions. All inclusions before casting are called primary oxidation inclusions. They can be divided into two types according to their size: one is a large inclusion with uneven distribution in the macroscopic structure, which makes the alloy structure discontinuous and reduces the compactness of the casting. Become the source of corrosion and the source of cracks, thereby significantly reducing the strength and plasticity of the alloy; the other is the fine dispersion inclusions, which can not be completely removed by refining, which increases the viscosity of the melt and reduces the aluminum liquid during solidification. The ability to supplement. The secondary oxidation inclusions are mainly formed during the casting process. When pouring, the aluminum liquid is in contact with air, and oxygen and aluminum act to form oxide inclusions. The aluminum alloy is in contact with various components in the furnace gas during the smelting process to form a compound such as AL2O3. Al2O3 in the aluminum liquid increases the hydrogen content of the aluminum alloy melt. Therefore, the AL2O3 content in the aluminum liquid has a great influence on the formation of pores in the aluminum casting.
2. Filtration purification method
Foam ceramic filtration technology appeared in the 1970s, and the use of foam ceramic filter plates is the most effective way to remove inclusions in the aluminum melt. As for the metal filter and the fiber cloth filtration, only the large inclusions in the aluminum alloy melt can be removed, but the inclusions below the micron level cannot be removed, and the metal filter can also contaminate the aluminum alloy. The use of foam ceramic filter plates can filter out fine inclusions and significantly improve the mechanical properties and appearance quality of castings. It is the primary choice for the casting workshop.
3. Use and selection of filter plates
The foam ceramic filter plate is installed in a filter box between the furnace mouth and the splitter plate. The filter box is made of "Zhong Na 5" refractory material, which can pass through multiple chilling heat without cracking, and has high strength. The advantages of good thermal insulation performance are the best materials for making filter boxes and launders. The closer the filter box is to the shunt plate, the better, because it reduces the flow distance after the aluminum liquid is filtered and reduces or prevents the re-generation of oxide. The aluminum liquid flows out of the furnace through the filter box and then flows into the manifold through the flow cell. When the filter device is started, the drop before and after melt filtration is about 50mm, but as the filtration time increases, the inclusions on the surface of the filter plate and the wall of the filter wall increase, the filtration flow rate decreases, and the difference between the front and the back increases. By the end of the casting, the drop increases. Up to 60-120 mm. The filter plate must be selected according to the flow rate of the aluminum liquid. Secondly, the cleanliness of the melt, the maximum content of the inclusions and the total melt throughput should be considered. When designing the filter device, it should be ensured that the filter plate is immersed in the aluminum liquid during melt casting according to the specifications of the selected filter plate and considering the drop of the furnace mouth and the splitter plate. In addition, it must be considered that the installation and disassembly are safe and convenient, and the aluminum liquid in the filter box can be completely discharged after the melt casting. The surface of the filter plate has proven to be the most effective tool for removing oxidized inclusions in the melt. General fiber filtration can only remove large inclusions, while ceramic foam filter plates can filter out large inclusions and fine inclusions at the same time.
4. Filter principle
The ceramic foam filter plate has a multi-layer network, a multi-dimensional through hole, and a communication between the hole and the hole. During filtration, the aluminum liquid carries the inclusions along the tortuous channels and pores, and is directly intercepted, adsorbed, deposited, etc. when in contact with the foam-like skeleton of the filter plate. When the melt flows in the holes, the filter plate passage is curved, and the melt flowing through the passage changes the flow direction, in which the inclusions collide with the hole wall anvil and firmly adhere to the wall of the hole.
The main effect of the filter plate is its size and porosity to ensure that the larger the pores of the filter plate, the worse the slag removal effect. For aluminum castings with strict requirements, a filter plate with a small pore size should be selected.
Foam ceramic filter plates are currently the most effective tool for removing oxidized inclusions from the melt.
Friction And Wear Testing Machine
The machine is used to evaluate the loading capacity of lubricants in the process of sliding friction o na contact point under very high pressure. The above mentioned capacity including 3 datas to be tested: the maximum load PB under the unstuck condition, sintered load Pd and comprehensive value of wearing during friction ZMZ.
Friction And Wear Testing Machine,Wear Testing Equipment,Four Ball Friction Testing Machine,Friction And Wear Tester
Jinan Chenda Testing Machine Manufacturing Co., Ltd. , https://www.jncdtester.com