| Steel rings as an important component of the ring spinning machine,the number of which used on different types of ring spinning machines is between 600 and 1200,are consumed nearly 100 million a year.Antifriction performance of ring surface plays a pivotal role,which directly affects the spinning quality and productive efficiency.Internationally,the roughness and surface friction coefficient of steel rings are low in many advanced spinning companies.The speed of spinning can reach 25000 r/min and its service life is more than two years.However,the cost of production is too high.Domestic spinning enterprises mostly use common carbon steel or alloy steel rings with high ring surface friction coefficient.The speed of spinning is only 15000 r/min and the spinning efficiency is low.Meanwhile,high spindle speed results in poor spinning quality,high yarn hairiness and yarn breakage rate.Therefore,it is of great significance to study the friction reducing performance of steel rings for improving spindle speed and spinning quality.This dissertation focuses on 102Cr17 Mo stainless and polished steel ring,using magnetron sputtering technology to improve friction and wear resistance by coating on the surface of steel collar.The selection of test targets was according to the requirements of existing experimental equipment.Considering two key factors: sputtering self-lubricating soft film and hard film,three coating methods were designed experimentally: chromium film layer,self-lubricating graphite film layer,and titanium nitride hard film layer.After a lot of tests and comparison analysis: The friction coefficient of chromium-plated film reduced to about 0.6 by magnetron sputtering,which was not different from that of chromium-plated steel,but the adhesion of film substrate was strong;Graphite coating film base bonding force is low,and the effect of antifriction and wear resistance is poor;TiN coating has good antifriction and wear resistance but the bond strength needs to be further improved.To improve the friction and wear resistance and film-based bonding force simultaneously,the comprehensive analysis of the coating solution adopted Cr/TiN doublelayer film scheme which chose chrome as a based transition layer.The relationship between the friction coefficient of Cr/TiN film and the test variables was studied.Orthogonal design was based on the main factors affecting the friction coefficient of the film(nitrogen flow rate,coating time,coating power and furnace temperature).The relationship between the four main factors and the friction coefficient of the film was studied.According to the friction coefficient curve obtained and the analysis of the extreme difference of orthogonal test,the variation trend of antifriction properties of Cr/TiN films under different factors was obtained.The influence of experimental variables on the antifriction performance of the film was in the order of nitrogen flow rate,coating time,coating power and furnace temperature.The minimum friction coefficient obtained from the comprehensive analysis of the data of the influencing factors in the orthogonal test was 0.344.A single factor test was conducted on the nitrogen flow rate,which was the most important influence factor,and the anti-friction mechanism of the Cr/TiN double-layer membrane was analyzed.The surface morphology,atomic composition,and grain orientation of Cr/TiN films was analyzed by scanning electron microscopy,energy dispersive spectroscopy,and XRD.When the nitrogen flow rate was 20 sccm,the TiN was mainly(200)preferential orientation.The ratio of nitrogen atoms to titanium atoms was about 1:1 in the energy spectrum.At this time,the particles on the surface of the film,whose diameter was about 50 nm and the film was dense,were evenly distributed and generated stable TiN compound.The friction coefficient was 0.27.By synthesizing the results of orthogonal test,the optimum process parameters were obtained,and repeated tests were carried out.The friction coefficient of the film was stable in the range of 0.2 ~ 0.3.The properties of Cr/TiN films produced by optimum process parameters were tested.The mean value of adhesion test was 51.4 N,The average value of microhardness test using 25 g load was 11.7 Gpa;The average roughness of the film was 12.1 nm when the friction coefficient of the film was measured by rough degree instrument.Corrosion Resistance of thin films was assessed as Class 10.Comparative test on actual application of uncoated and coated collar on spinning Machine was conducted,Spinning quality standard required that the yarn hairiness H value was below 3,severed rate was below 20(root / 1000 h).Under this requirement,the ingot speed of coated steel collar can be increased from 15000 r/min to 18000 r/min.Spinning quality improved significantly,and the spinning efficiency can be increased by 20%. |
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