Forming aluminum-containing protective coating on surface of metal part, comprises placing metal part and cement in form of grains and made of aluminum alloy in chamber at treatment temperature and with atmosphere containing active gas

摘要

The method comprises placing a metal part and a cement in a form of grains and made of aluminum alloy including a reactive element such as zirconium and/or hafnium, in an chamber for treatment at a temperature and with an atmosphere containing an active gas, where the active gas reacts with the cement to form aluminum halide gas that breaks up in contact with the metal part into aluminum metal and to form halide of the reactive element that breaks up in contact with the metal part into the reactive element at the same time as the aluminum metal. The method comprises placing a metal part and a cement in a form of grains and made of aluminum alloy including a reactive element such as zirconium and/or hafnium, in an chamber for treatment at a temperature and with an atmosphere containing an active gas, where the active gas reacts with the cement to form aluminum halide gas that breaks up in contact with the metal part into aluminum metal and to form halide of the reactive element that breaks up in contact with the metal part into the reactive element at the same time as the aluminum metal. The cement grains present an aluminum rich phase. A rejuvenation of the cement grains is carried out by removal of a surface layer of the cement grains after a number of batches corresponding to disappearance of the aluminum rich phase of the surface layer. The cement grains has diameter of 1-30 mm. The cement grains include a chromium rich phase and a reactive element rich phase. The removal of the surface layer is carried out without the aluminum rich phase when the surface layer is more than 300 mu m. A thickness of the surface layer impoverished of the aluminum rich phase is measured by micrographic analysis. The surface layer is removed by sifting. The metal part and the cement grains are heated with gas in chamber at a room temperature until the treatment temperature is 1080[deg] C for 5-30 minutes.