Application experiment of supersonic spraying WC-10Co-4Cr in high pressure gate valve

       First of all, we grind and polish the coating to make the finish of the coating reach the level of Ra≤1, and then directly conduct the Vickers hardness test on the coated working surface of the valve plate, and the test pressure is 300g force. The test method is: randomly hit five points in the same field of view, and then take the average value of the five values obtained, which is the hardness value of the sample. Vickers hardness values tested on two specimens. The average hardness of the two samples is HV0.31200 or more. The indentation state of the coating is good, and there is no collapse at the indentation, indicating that the coating is relatively dense and uniform in hardness. At the same time, no cracks appear along the indentation, indicating that the coating has good toughness. The good density, toughness and relatively uniform microhardness of the WC-10Co-4Cr coating ensure that the coating has excellent wear resistance and good impact resistance.



Then carry out the coating pressure sealing test:



Firstly, the semi-quantitative analysis of the porosity of the coating was carried out using image analysis technology. Porosity test results of coatings obtained by spraying powders by JP8000 system. In the experiment, two fields of view of the coating cross-section were randomly selected for analysis. The porosity in the two fields of view is 1.6% and 1.4%, respectively, with an average porosity of 1.5%.



Then, the water pressure sealing test was carried out on the sprayed samples. Before the experiment, the coating on the working surface of the valve plate was finely ground and polished, and then the pressure resistance test was carried out under the water pressure of 100Mpa (ultra-high pressure), and the pressure duration was 30 minutes. After the pressurization is completed, the experimental results show that there is no "sweat" or water seepage on the working surface of the valve plate, indicating that the sealing effect is good, and there will be no leakage under the water pressure of 100Mpa.



Therefore, a coating with a porosity level of about 1.5% can be obtained, which can meet the requirements of water pressure sealing below 100Mpa.



Summarize:



Using supersonic spraying process and WC-10Co-4Cr powder spraying material, the working face of the valve plate is sprayed and strengthened, and the following conclusions are drawn:



(1) The bonding strength of the coating reaches 72.63Mpa, and the bonding state between the coating and the substrate is good;



(2) The Vickers hardness value (HV0.3) of the coating is 1257.1, the microscopic hardness value of the coating is uniform, and the coating density and toughness are good;



(3) The porosity of the coating is about 1.5%. Through the 100Mpa water pressure resistance test, there is no leakage phenomenon on the working surface of the valve plate, indicating that the coating has good density, and the porosity level meets the working needs of the high-pressure gate valve.



Therefore, it is shown that through supersonic spraying of WC-10Co-4Cr, the high-pressure gate valve can fully meet the user's requirements in work.