The relationship between bearing material and performance
Blackening treatment now commonly used methods are the traditional alkaline heating blackening and the late room temperature blackening.But the blackening process at room temperature is not good for low carbon steel.A3 steel is better blackened with alkali.Alkaline blackening is subdivided and there is a difference between once blackening and twice blackening.The main components of the blackening solution are sodium hydroxide and sodium nitrite.Blackening requires a wide range of temperatures, between 135 degrees Celsius and 155 degrees Celsius, to produce a good surface, but it takes a little longer.In actual operation, it is necessary to pay attention to the quality of derusting and oil removal before the workpiece blackening, as well as the passivation of oil immersion after blackening.The quality of blackening often varies with these processes.
Metal "blue" solution
Alkaline oxidation method or acid oxidation method;An oxide film is formed on the metal surface to prevent corrosion. This process is called bluing.The oxide film formed on the black metal surface after "blue" treatment is mainly iron tetroxide in the outer layer and ferrous oxide in the inner layer.
One, alkaline oxidation method "blue" liquid medicine
1.Formula: sodium nitrate 50 ~ 100 g sodium hydroxide 600 ~ 700 g sodium nitrite 100 ~ 200 g water 1000 g
2.Method: according to the formula after measurement, in the stirring conditions, in turn to the material into which, dissolved, mixed evenly.
3.Description:
(1) the metal surface must be washed and dried before the "basket" treatment.
(2) the "blue" treatment conditions of metal devices are related to the carbon content in the metal, the temperature of the "blue" solution and the treatment time of metal devices.
(3) regularly analyze the contents of sodium nitrate, sodium nitrite and sodium hydroxide in the solution every other week or so, so as to timely supplement the relevant components.General use after half a year should replace all solution.
(4) after the "blue" treatment of the metal, it is best to rinse it with hot soapy water for a few minutes, then rinse it with cold water.Then rinse with hot water and blow-dry.
Two, acid oxidation method "blue" solution
1.Formula: 3 ~ 10 g phosphate calcium nitrate 80 ~ 100 g manganese peroxide 10 ~ 15 g water 1000 g
2.Method: after measuring by formula, under the condition of constant stirring, successively add phosphoric acid, manganese peroxide and calcium nitrate, dissolve and mix evenly.
2.Description:
(1) the metal devices can be cleaned and dried before the "blue" treatment.
(2) the protective film obtained by this method is black, and its main component is composed of oxides of calcium phosphate and iron. Its corrosion resistance and mechanical strength are both higher than those obtained by alkaline oxidation method.
4. The working temperature of "bluing" is 100℃, and the processing time is 40 ~ 45 minutes.In the treatment of carbon steel, the phosphoric acid content in the solution is controlled at 3 ~ 5 g/l.When treating alloy steel or cast steel, the phosphoric acid content is controlled at 5 ~ 10 g/l.Attention should be paid to the periodic analysis of phosphoric acid content of the liquid.
5. The cleaning method of metal devices after "bluing" treatment is the same as above.