| China is developing rapidly as a major cotton-producing country,and Xinjiang is the main cotton-producing region in China is more prominent.In order to reduce manpower and material resources,saving picking costs,mechanized harvesting has become the main way of cotton harvesting.Cotton picker picking spindle is the core work parts,its surface performance is related to the quality and efficiency of picking.In recent years,cotton picking machine picking spindle has been the focus of research,the existing market picking spindle using electro-chromium plating as the surface wear-resistant layer,but the production process of electro-chromium plating will cause serious environmental pollution,and electro-chromium plating surface there are a large number of micro-cracks,affecting the mechanical properties.In this study,we analyzed the mechanism of picking spindle and chromium substitution process,and chose PVD process to prepare TiN coating on the surface of picking spindle to replace chromium plating coating,and analyzed the microscopic morphology of picking spindle treated by PVD technology with the help of laser confocal microscope and scanning electron microscope.The nano-hardness and elastic modulus of PVD-TiN and chromium-plated ingots were tested by friction and wear testing machine,and finally field tests were conducted to verify the surface properties of the two types of spindles.(1)The PVD-TiN coating has a tight structure and uniform particle distribution on the surface,with "island" characteristics and no obvious pores and cracks.The electroplated chromium coating has obvious defects such as micro-cracks and concave holes.The roughness of TiN coating prepared by PVD process on the surface of picking spindle of cotton picker is lower than that of electrochromic coating.(2)The surface nano-hardness of PVD-TiN coating is 20.57 GPa,which is about 2.5 times of that of electro-chromium plating coating,and the H/E value is 0.0937,which is about 2.2 times of that of electro-chromium plating coating,with better surface mechanical properties.(3)The wear mechanism of PVD-TiN coating is mainly abrasive wear,while the wear mechanism of electrochromic coating is mainly adhesive wear.In the friction experiments,the abrasion marks of PVD-TiN and chromium plating coatings gradually deepen and widen as the friction time increases.However,the depth of wear marks and the amount of wear on the surface of PVD-TiN coating are much smaller than those of electrochromic coating.Under different loads and different friction frequencies,PVD-TiN coating shows lower friction coefficient,which proves that PVD-TiN coating has lower friction power consumption.(4)The field test results show that the average wear area of electrochromic picking spindle hook teeth is larger than that of PVD-TiN picking spindle,which proves that the wear resistance performance of PVD-TiN picking spindle is better than that of electrochromic picking spindle in actual work.This study uses PVD technology to deposit TiN coating instead of the traditional chromium plating on the picking spindle surface,which has some practical engineering significance to improve the wear resistance and service life of the picking spindle surface,and provides reference for the modification of the picking spindle surface of cotton picking machine. |
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