Vacuum carburizing method and device

Abstract

A method and a device for carburizing at subatmospheric pressures. According to said method, a treatment gas containing hydrocarbons is supplied to a treatment chamber and an exhaust stream exits said chamber. The opacity of the gas atmosphere that prevails in the treatment chamber and/or the opacity of the exhaust stream that exits said chamber is/are determined and the supply of the treatment gas containing hydrocarbons to the treatment chamber is regulated in accordance with the opacity that has been determined. If an opacity value that has been set or can be set is exceeded, the supply of the treatment gas containing hydrocarbons to the treatment chamber can be interrupted, or the quantity of treatment gas containing hydrocarbons that is supplied to said chamber can be reduced.

1 . A method of carburizing carburizing, at subatmospheric pressures, a treatment gas containing hydrocarbons being supplied to a treatment chamber and an exhaust stream exiting from the treatment chamber, comprising the steps of: 
 determining the opacity of the gaseous atmosphere prevailing in the treatment chamber and/or the opacity of the exhaust stream exiting from the treatment chamber and, as a function of the determined opacity, regulating the feeding of the hydrocarbon-containing treatment gas into the treatment chamber.    
   
   
       2 . A method according to  claim 1 , further comprising the step of interrupting the feeding of the hydrocarbon-containing treatment gas into the treatment chamber when an opacity value, which is set or can be set, is exceeded.  
   
   
       3 . A method according to  claim 1 , further comprising the steps of reducing the quantity of the hydrocarbon-containing treatment gas fed to the treatment chamber when an opacity value, which is set or can be set, is exceeded.  
   
   
       4 . A method according to  claim 1 , wherein a pressure between 3 and 20 mbar is set in the treatment chamber.  
   
   
       5 . A method according to  claim 1 , wherein alkanes, alkenes, alkines or derivatives of the afore-mentioned, to which hydrogen can be admixed, are used as hydrocarbon-containing treatment gas.  
   
   
       6 . A device for carburizing at subatmospheric pressures comprising: at least one treatment chamber, at least one feeding line, by way of which a treatment gas containing hydrocarbons is fed to the treatment chamber, and at least one evacuating line by way of which the exhaust stream is withdrawn from the treatment chamber by means of an evacuating device, 
 wherein at least one valve is arranged in the feeding line, at least one device for determining the opacity of the gaseous atmosphere prevailing in the treatment chamber is arranged in the treatment chamber, and/or at least one opacity probe is arranged in the evacuating line, and an analyzing unit is provided which, as a function of the opacity of the exhaust stream determined by means of the device for determining the opacity of the gaseous atmosphere prevailing in the treatment chamber, and/or by means of the opacity probe, regulates the feeding of the hydrocarbon-containing treatment gas into the treatment chamber by means of driving the valve.    
   
   
       7 . A device according to  claim 6 , wherein the valve is a control valve.  
   
   
       8 . A device according to  claim 6 , wherein the analyzing unit permits the setting of an opacity limit value.