Study On The Friction And Wear Properties Of Gray Cast Iron After Laser Biomimetic Coupling Treatment Under Starved Lubrication

Gray cast iron is widely used in modern industry due to its good machinability,wear resistance and low price.In addition,the graphite contained in the gray cast iron is not only a good lubricant,it can has a lubricating effect in the friction and wear process;but also absorb the vibration of the cast iron parts and weaken the vibration energy transfer between the crystal grains,so that gray cast iron has good shock absorption.Therefore,gray cast iron is also commonly used as a material for manufacturing precision machine tool guides.In recent years,with the continuous development of the industrial process and the release of the "Made in China 2025" strategic goal,higher requirements have been placed on the development of machine tools.As an important part of the machine tool system,the machine tool guide rail has a decisive effect on the machining accuracy and machining quality of the machine tool,and even affects the overall service life of the machine tool.Therefore,improving the wear resistance of the machine guide rail of the gray cast iron has important practical significance for ensuring the processing quality of the machine tool and prolonging its service life.For the improvement of the wear resistance of machine tool guides,the idea of biocoupling bionics provides us with new ideas and ideas.Our research group uses laser biomimetic coupling technology to process the “plane biomimetic unit” of the hard phase on the surface of gray cast iron,so that it forms a soft and hard special structure with the substrate,and change the shape of the biomimetic unit(point,strip,net)to improve the wear resistance of gray cast iron.On the basis of previous studies,based on coupled biomimetic theory,inspired by the morphological and structural characteristics of nonsmooth surface of organisms,and combined with the actual working environment of machine tool guideways is under starved lubrication conditions.Laser technology was used to process "groove biomimetic unit" on the surface of gray cast iron to couple it with “plane biomimetic unit”,so as to further improve its wear resistance,and the influence rule and wear resistance mechanism were summarized.In this paper,the effects of plane biomimetic unit,groove biomimetic unit and its characteristic quantities on the wear resistance of gray cast iron under starved lubrication were investigated.In the research process,the groove biomimetic units with different crosssectional geometric sizes were obtained by changing the laser processing parameters,which were coupled with plane biomimetic units,and their influence on wear resistance was explored.The microstructure phase analysis and micro-hardness measurement of these two different biomimetic units were also carried out.Secondly,based on the previous step,this paper changed the orientation and spacing of groove units,and combined wear test with finite element stress analysis to study the influence of different orientation and spacing of groove biomimetic units on wear resistance.The research shows that the coupling between the plane biomimetic unit and the groove biomimetic unit can effectively improve the wear resistance of the gray cast iron surface.Among them,when the laser processing parameters are current 255 A,pulse width 0.3 ms,frequency 50 Hz,defocusing amount 0 mm,scanning speed 0.5 mm/s,the groove biomimetic unit has the greatest improvement in wear resistance.In addition,the wear resistance of gray cast iron will increase first and then decrease as the orientation and spacing of the groove biomimetic unit increases.When the plane biomimetic unit is coupled with a groove biomimetic unit with an orientation of 45° and a spacing of 3 mm,the sample has the best wear resistance,and its wear resistance is improved by 71.3 % compared with the untreated sample.