Advances in carburizing technology

Carburizing is one of the most widely used process methods in the automobile and tractor industry. In the 1950s, the transition from solid carburizing to gas carburizing in which liquid infiltrant was dripped into the well furnace was realized, which improved product quality and improved work efficiency. After the LiCl dew point meter was successfully developed in the early 1960s, the controlled carburization of methanol and acetone was first realized on the pit carburizing furnace. After mastering the preparation method of the endothermic atmosphere and successfully developing the sealed carburizing furnace, the carbon potential control of the sealed carburizing furnace was realized with a dew point meter. In the late 1960s, an infrared carbon dioxide analyzer was successfully developed. In order to improve the accuracy of carbon potential control, infrared instruments were popularized in the 1970s, mainly used for drip carburizing of pit furnaces. At present, controllable carburization using drip methanol and kerosene has reached a fairly popular level. Especially after the introduction of a large number of drip-type sealed carburizing furnaces and a variety of microprocessor programmable controller carbon potential controllers came out in the late 1970s and early 1980s, they have also been widely used in sealed multi-purpose furnaces.

Due to the dripping of methanol and kerosene into the furnace, the carbon monoxide composition in the furnace gas is unstable, and the methane content also reaches 1% to 2%. The single-factor control using only the carbon dioxide infrared meter can achieve a control accuracy of ±0.05%. For this reason, they have researched and developed instruments and methods for multi-factor carbon potential control of carbon dioxide, carbon monoxide and methane.

Because the raw materials for the preparation of endothermic gas-natural gas and liquefied petroleum gas are in short supply, and methanol is used in large quantities, the production cost is high, forcing industrial production to find other outlets. The emergence of carbon molecular sieve pressure swing adsorption nitrogen production (PSA method) technology has created conditions for solving this problem. In the early 1980s, the domestic carbon molecular sieve system was successfully developed. Then the synthetic atmosphere carburizing method using nitrogen-based atmosphere, methanol and ethyl acetate (or kerosene) came into being. At the same time, the measurement and control technology and instruments of atmospheric trace oxygen (oxygen potential) were introduced. At present, the method of carburizing using nitrogen-based synthesis atmosphere and furnace gas control technology of oxygen probe, and using a microprocessor to control the carbon potential and the depth of the carburizing layer have been widely used in production. Individual factories have also introduced Supercarb direct carburizing equipment and processes. At present, the controllable carburizing, carbonitriding, and nitrocarburizing technologies in the automobile, motorcycle, engineering machinery, bearing, gear, and fastener industries have reached a considerable degree of popularity. spring

Since the 1980s, local equipment manufacturing companies have been able to produce series of sealed multi-purpose furnaces, push rod continuous furnace carburization, quenching, cleaning, and tempering production lines, and mesh belt furnace production lines. There is a corresponding carbon potential and automatic process control system for commodity production and supply. Since the 1990s, internationally renowned equipment manufacturing companies have successively established joint ventures and wholly-owned production plants in China, providing heat treatment companies with advanced equipment with high reliability and acceptable prices. For this reason, it has also stimulated and improved the manufacturing level of local equipment manufacturers, and created good conditions for the heat treatment technology transformation and equipment renewal of the private, joint-stock heat treatment processing enterprises and state-owned large factories that have emerged in the past decade.