The Research On The Preparation Of Wear-Resistant Coating In The Screw Surface Of Biomass Forming Machine

Spiral Extrusion Machine is the earliest and most widely used production equipment in the biomass curing molding technology.The screw is the core working part of the screw extrusion machine.The screw is wear seriously with the material in high-speed dry friction,leading to the short life of screw,which is seriously hampered the efficiency of the screw extrusion machine.At present,most of the methods to improve the wear resistance of the screw are mainly based on the repair and surface modification methods.However,there are some problems remains to be solved,such as the frequently disassemble of the screw,the complex process,the high standard of the work-piece structure,and so on.TD method has many advantages,such as simple operation,low cost,high cladding hardness and strong bonding strength.In recent years,it has been widely used in steel surface modification at home and abroad.In this study,the vanadium carbide wear layer was prepared on the surface of screw by vanadium permeation of TD salt bath.The study systematically inspected the effect of salt bath process parameters on the coating thickness,composition,structure and coating performance.The 45 steel materials were prepared by different treatment processes.And the relationship between process conditions,coating structure and performance was discussed.Finally,the preparation process of screw coating preparation is optimized.Based on the optimization of the processing parameters,it was explored that the processing parameters and their processing flow of the surface preparation of carbon vanadium compounds wear resistant coating on the screw Extrusion Machine Screw Common Material 45 Steel.This study provided new ways and technical support to further extend the life of the screw,improve the spiral extrusion molding machine to promote the level of production,and expand the scope of application.The main conclusions of this study are as follows:(1)Under the treatment temperature of 900 °C,950 °C,100 °C,and the treatment time of 2 h,5 h,8 h,the thickness,the thickness of the cladding layer was measured by scanning electron microscopy(SEM).The results show that the thickness of 45 steel coating increases with the increase of treatment temperature or treatment time,and the growth rate gradually decreased.The kinetic analysis of the growth of the coating shows that the growth curve of the coating thickness with time.At different treatment temperatures,the value of the index n of the cladding growth is better than that of the model.(2)Through the spectrometer and electron probe,the coating composition of different processing parameters was detected.The results show that the coating contains the elements of C and V,without the other elements.There is a clear interface between the cladding and the substrate.And there existed the phenomenon that trace elements spread with each other,with the diffusion region of about 2 ?m.The structure of the coating was analyzed by X-ray diffractometer.The results show that the coating consisted VCx compound composition with different carbon vanadium ratios.Wherein,the highest content of VC led to the best crystallinity.By the multiple use of salt bath,the quality of the coating was studied.Without adding additional ingredients other than the recipe,the salt bath can be used for about four times.With the increase of repeated times of use,the coating quality was decreased.(3)The cladding hardness and friction-wear properties were detected via different treatment processes through the micro hardness tester,friction and wear test machine.It was shown that the cladding could achieve higher hardness and friction-wear properties under the treatment conditions of high temperature and long time.The friction factor of TD salt coating is 0.44 times than that of the original sample,and anti-wear of TD salt coating is 3 times than that of the original sample.The optimum treatment parameters were 950 ? and 8 h.The improvement of the 45 steel screw structure saved the TD processing raw materials and the time cost of coating preparation.And the wear-resistant coating was successfully prepared on the surface of the screw under the optimization process..