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Carburizing process with pre-vacuumizing, protecting nitrogen-base atmosphere and no inner oxidation

A vacuum nitrogen-based, internal oxidation technology, applied in metal material coating process, coating, solid diffusion coating and other directions, can solve the problems of undetectable and controllable carbon concentration, slow speed, large initial investment, etc., to overcome conventional The effect of uneven gas carburization, overcoming internal oxidation, and avoiding internal oxidation

Inactive Publication Date: 2006-10-18
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantages of this technology are: 1) the carbon concentration in a vacuum environment cannot be detected and controlled at present; 2) the existing well-type carburizing furnace and box-type multi-purpose furnace cannot be used, and the initial investment in equipment is very large
use N 2 +C 3 h 8 Protective carburizing is easy to produce carbon black; use N 2 +CH 4 +CO 2 The speed of protective carburizing is slow, and internal oxidation occurs
These factors restrict the promotion and application of the above technologies in industry

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0010] First, put the workpiece into the well-type carburizing furnace and pre-vacuumize it. When the furnace pressure reaches 100Pa, then fill the furnace with nitrogen with a purity of 99.9%-99.9999%, and adjust the pressure to 1.02×10 5 Pa, turn on the heater and start the circulating fan in the furnace at the same time. The rotating speed of the circulating fan in the furnace is 1000rpm. When the temperature rises to 980°C, fill the furnace with acetylene, and the partial pressure is 10000Pa. The speed is adjusted to 500rpm, and the workpiece is oil-quenched after 60min. In this example, the carburized layer is relatively uniform, and the carburized layer has no internal oxidation.

Embodiment 2

[0012] First put the workpiece into the box-type multi-purpose furnace for pre-vacuumizing. When the furnace pressure reaches 10Pa, then fill the furnace with nitrogen with a purity of 99.9%-99.9999%, and adjust the pressure to 1.1×10 5 Pa, turn on the heater, and start the circulating fan in the furnace at the same time. The rotating speed of the circulating fan in the furnace is 1400rpm. The speed is adjusted to 700rpm, and after 60min, the workpiece is transferred to the cooling chamber for quenching. In this example, the carburized layer is relatively uniform, there is no carbon black on the surface, and there is no internal oxidation in the carburized layer.

Embodiment 3

[0014] First, put the workpiece into the well-type carburizing furnace and pre-vacuumize it. When the furnace pressure reaches 10Pa, then fill the furnace with nitrogen with a purity of 99.9%-99.9999%, and adjust the pressure to 1.04×10 5 Pa, turn on the heater, and start the circulating fan in the furnace at the same time. The rotating speed of the circulating fan in the furnace is 700rpm. The speed was adjusted to 500rpm, and after 120min, the workpiece was transferred to the cooling room for air cooling. In this example, the carburized layer is relatively uniform, and the carburized layer has no internal oxidation.

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Abstract

The carburizing process with pre-vacuumizing, protecting nitrogen-base atmosphere and no inner oxidation belongs to the field of heat treatment technology of metal material. The present invention has the hot treating furnace pre-vacuumized to 10-100 Pa, introduced with high purity nitrogen and heated to 900-1050 deg.c, before maintaining and introducing acetylene gas to carburize at nitrogen pressure of 0.1-0.11 MPa and acetylene gas pressure of 5000-20000 Pa. The present invention has no carbon black production, environment friendship, less oxidation of workpiece, low cost and high safety.

Description

technical field [0001] The invention relates to a carburizing method, in particular to a carburizing method without internal oxidation under the protection of a pre-evacuated nitrogen-based atmosphere, and belongs to the field of heat treatment of metal materials. Background technique [0002] In order to improve the quality of chemical heat treatment and reduce defects such as carburizing and internal oxidation, low-pressure carburizing methods are usually used. Low-pressure carburizing is a new type of carburizing technology developed on the basis of gas carburizing and vacuum quenching technology. The workpiece is heated in a vacuum environment, and a certain pressure of hydrocarbons is introduced for carburizing, which is catalyzed on the surface of high-temperature metals. Under the action, the hydrocarbons are decomposed into free carbon and hydrogen, and the high-concentration carbon is adsorbed by the high-temperature workpiece surface, so as to achieve the purpose o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/34
Inventor 左训伟陈乃录张伟民郝晓伟廖波
Owner SHANGHAI JIAO TONG UNIV
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