| Under the complex working conditions of coal mine,there is serious wear of coal mine machinery,and the wear is often the result of the joint action of various wear types.At present,there are few studies on the wear characteristics of multiple wear types,which leads to the lack of reference data in equipment design,and the selection of materials depends on experience.In addition,the lack of test equipment that can fully simulate the actual working conditions has hindered the development of new wear-resistant materials and the research on the wear characteristics under the actual working conditions.Therefore,it is of great significance to develop a multi-mode friction and wear testing machine,study the wear characteristics of materials under the coupling effect of multiple wear types,and predict the wear of materials at the same time,for the selection of mechanical wear parts of coal mine according to the location,guarantee the safety production of coal mine,and improve economic benefits.This paper was supported by the sub-project “Research and Application Demonstration of Application Technology of High Wear Resistance Steel Plate for Coal Mining”(No.: 2017YFB0305105)of the “13th Five-Year Plan” National Key R&D Program of China “High Wear-Resistant Steel Plate for Coal Mining and Application”.Using modern tribological theory,combined with advanced experimental methods and statistical regression analysis method,a comprehensive and systematic study was conducted on the wear characteristics of a new type of high-titanium low alloy wear-resistant steel,and a comparative analysis was conducted with the typical wear resistant steel NM400.On this basis,a prediction model which can better reflect the actual wear of materials is established.Firstly,a multi-mode sliding friction and wear testing machine is designed and developed according to the complex and harsh working conditions of coal mine,which integrates the test functions of three commonly used testing machines: sliding friction and wear testing machine,wet abrasive wear testing machine and dry abrasive wear testing machine.Automatic control of loading and sliding speed,real-time display and automatic storage of test parameters such as friction coefficient,positive pressure,sliding speed and p H value of corrosive liquid are realized.The effectiveness,uniformity and repeatability of the testing machine and its function of simulating the actual working conditions of wear-resisting materials used in coal mine were tested.Secondly,abrasive-sliding wear test,corrosion-sliding wear test and abrasive-corrosion-sliding wear test were carried out using the testing machine.The effects of coal gangue content,p H value of simulated mine water,load and sliding speed on the wear characteristics of ZM4-13 were analyzed,and compared with NM400.Surface microscopic morphology,element distribution and surface profile analysis,analyzed the wear mechanism,and on the basis of the established model of abrasive-sliding wear,corrosion-sliding wear and abrasive-corrosion-sliding wear,and respectively mapped the abrasive-sliding,corrosion-sliding and abrasive-corrosion-sliding wear mechanism.Thirdly,based on the above analysis of wear characteristics and mechanism,the wear prediction models of ZM4-13 and NM400 were established by using uniform experimental design and regression analysis method,taking the main working conditions of coal mine machinery as factors.The difference between the predicted value and the test value and between the predicted value and the actual value was compared and analyzed.The main conclusions are as follows:1)The wear tester has a good simulation function of actual working conditions,and the macroscopic and microscopic morphology of the sample after grinding is similar to the actual wear morphology,and the wear mechanism is the same.The test results of the tester have good repeatability,the average error of the wear quantity of the repeated test sample is 2.1%,and the wear degree of the micro surface is basically the same after grinding.2)In the state of abrasion-sliding wear,the main wear mechanism of ZM4-13 is adhesive wear when hard abrasive content is low.With the increase of hard abrasive content,the plowing effect of abrasive on the surface of ZM4-13 increases,which aggravates abrasive wear.The wear mechanism of ZM4-13 is changed from adhesive wear to the joint effect of abrasive wear and adhesive wear.The Ti C particles in ZM4-13 disperse in the matrix and partially improve the hardness of the matrix.The Ti C concentration zone can hinder or weaken the plowing effect of hard particles on the friction contact surface,thus improving the wear resistance of ZM4-13.The wear resistance of ZM4-13 is 1.1-1.3 times that of NM400,and the wear resistance is more outstanding under the condition of high content of coal gangue.ZM4-13 is not only suitable for general working conditions,but also for harsh working conditions of high content of coal gangue.3)In the state of corrosion-sliding wear,O,S and other elements in the mine water diffuse to the surface of the material,forming hard and brittle oxides,soft sulfides and so on.Under the relative sliding movement of the grinding parts,these chemical substances constantly fall off from the surface,resulting in the loss of the material.Acid and alkaline mine water conservancy is responsible for the diffusion of O,S and other elements to the material deformation layer,while neutral mine water is not conducive to its diffusion.Under the condition of neutral and alkaline mine water,the wear mechanism of ZM4-13 is mainly corrosion wear.Under the condition of acidic mine water,the wear mechanism of ZM4-13 is corrosion wear and adhesive wear.The diffusion effect of O,S and other elements is strengthened,which makes the wear mechanism of ZM4-13 change from corrosion wear to corrosion wear and adhesive wear.Ti C particles are dispersed in the material matrix and partially improve the hardness of the material.High local hardness reduces the plastic deformation in the process of material wear,weakens the diffusion of O,S and other elements,and hinders the interaction between adhesive wear and corrosive wear,thus improving the wear resistance of the material.The wear resistance of ZM4-13 is 1.4-1.9 times that of NM400,and the anti-wear performance is more outstanding under neutral mine water condition.4)In the state of abrasive-corrosive-sliding wear,the plough effect of abrasive on material surface increases with the increase of gangue content,which can aggravate the abrasive wear of material.Acid and alkaline mine water can promote the diffusion of O,S and other elements into the deformation layer of materials,and promote the corrosion and wear of materials.The increase of load will promote adhesive wear and abrasive wear.Under acid,high content of coal gangue and heavy load conditions,the interaction of abrasive wear,corrosion wear and adhesive wear is more prominent,and ZM4-13 and NM400 produce serious wear.In the condition of neutral,medium and low content of coal gangue,the wear mechanism of ZM4-13 and NM400 is mainly abrasive wear,and slight wear occurs in ZM4-13 and NM400.The wear resistance of ZM4-13 is 1.1-2.1 times that of NM400,and the anti-wear performance is more outstanding under the conditions of high content of coal gangue,heavy load and neutral mine water.The high hardness of Ti C precipitation area in ZM4-13 hinders the plowing of hard particles,the sliding of grinding parts and the plastic deformation of surface materials,so ZM4-13 is more wear-resistant than NM400,especially suitable for the harsh working conditions of coal mine production.5)The wear prediction models of ZM4-13 and NM400 consider the presentage of coal gangue,p H value of simulated mine water,load,speed and other main working conditions of coal mining machinery.The fitting degree of predicted value and experimental value,predicted value and actual value are good,which can better predict the actual wear of materials,providing a basis for the design selection of materials for coal mining machinery. |
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