Research On Micro-arc Plasma Surface Cladding Of Mine-used Pick And Secondary Injection B₄C Composite

Pick is one of the largest mining machinery parts in coal mining process.In order to improve its service performance and life,the micro-arc plasma surface cladding and secondary implantation of B₄C were used to strengthen the surface of mining pick.The cladding layer of 1Cr13 stainless steel Fe-based self-fluxing alloy powder with 5%,10%,15%B₄C and 1:9 mechanical mixing of B₄C particles and main material was studied.The optimum process parameters of plasma cladding and B₄C secondary injection were determined by analyzing the process of B₄C secondary injection.The microstructure and properties of the alloys with different B₄C injection amount were analyzed,and industrial experiments were carried out.The 1Cr13 stainless steel iron matrix of the main cladding material was injected into different amounts of B₄C particles and the cladding samples were prepared.The microstructure and morphology of the samples were observed by optical microscope and scanning electron microscope,and the phase composition was analyzed by X-ray diffraction.The mechanical properties of the specimens were tested by microhardness tester and Rockwell hardness tester.The wear resistance tests were carried out,and the cladding process parameters were optimized.The specific technological parameters of the spiral cladding layer of the main material with a height of 1¹.5mm and smooth lapping are as follows:the height between the nozzle and the pick is 9¹1 mm;the distance between the nozzle center and the pick axis is 2³mm;The ion gas flow rate is 8 L/min and the cladding current is 85⁹5A.The powder feeding rate per unit time is 26²8 g/min,the lap ratio is 25%,and the plasma torch speed is 550⁶50 mm/min.By adjusting the parameters of the two injection powder feeding system,the same injection volume is obtained.Microstructure observation shows that most of the Fe-based self-fluxing alloy powders of 1Cr13 stainless steel are dendritic after cladding,and the phase of the alloy layer is mainly composed of gamma-?Fe,Cr?and carbide phase,and the microstructure of the alloy layer in the upper and middle parts is mainly slender rod-like structure;when the B₄C content is 10%,the phase of the alloy layer is mainly composed of gamma-?Fe?,CrB,and carbide phase.B₄C,Fe₂B and Fe₂₃?C,B?₆phases are composed,and the equiaxed grain size is the smallest in the upper part of the alloy layer.When B₄C is mechanically mixed with iron-based alloy powder at a ratio of 1:9,the alloy layer is mainly composed of gamma-?Fe?,CrB,Fe₂B and Fe₂₃?C,B?₆ phases,and the equiaxed grain size is coarse.The effect of different B₄C particles on the microstructure and phase composition of the main material 1Cr13 stainless steel Fe-based alloy layer is different.When the B₄C particles content is 10%,the equiaxed grain size of the incompletely melted B₄C particles in the alloy layer is the smallest and uniform,which improves the hardness and wear resistance of the cladding layer.The hardness and wear resistance were tested.When the content of B₄C particle was 10%,the microhardness of alloy layer was the highest,the wear weight loss was the smallest,and the strength and wear resistance of pick surface were the best.The"integrated"production technology is adopted for the sparkless pick,which improves the production efficiency,reduces the cost,enhances the wear resistance and prolongs the service life.