| Friction and wear consume 50% of the world’s energy, and the economic loss caused by friction and wear is very large, of which the wear of agricultural cultivation is one of the major energy consumption. Touching soil parts of agricultural machinery usually can not reach the requirements of the agricultural work causing by wear and tear problems, which result in their frequent failure, high operation cost, and even missing farming season. This is a problem of farm machinery field to be solved at present. Traditional single hardening methods such as surface deformation strengthening, surface hardening, surface element diffusion heat treatment, surface coating, chemical and physical vapor deposition, etc. often failed to improve the wear resistance of the agricultural touching soil parts because those methods usually couldn’t take the soil complex work environment and diversity of wear property into consideration, which result in some drawbacks such as poor impact resistance, chemical corrosion resistance and resistance to permeability. In this paper, according to the characteristics of the working environment of soil engagement implements, Ti Nx/CFy composite coatings on 65 Mn steel substrate using magnetron sputtering method have been prepared. The composite coatings contain both direct load bearing hard phase Ti Nx and the soft phase CFy supporting the hard phase, aiming in achieving better abrasion resistance. In addition, the soft phase CFy can reduce adhesion and corrosion wear owing to its low surface energy and hydrophobic effect. In this paper, the design and preparation of the coating were studied, the coating preparation process was explored, also the structure of the coating composition and the properties of the coating were studied.The set up is a magnetron co-sputtering system consisted of cylindrical Ti target and PTFE target which were placed separately at the two sides of the substrate. Taking the advantage of uniform and density characteristics of the coating prepared by the magnetron sputtering process, PTFE is designed as twin cylindrical magnetron target, which would become the soft phase CFy in the deposition process. Hard phase Ti Nx is the body of anti-wear, which is grown by reactional sputtering cylindrical Ti target with N2. The main controlled parameters for the magnetron sputtering of the deposition process include magnetron co-sputtering power ratio, bias voltage, nitrogen partial pressure, deposition time, rotation speed, etc. Studies have shown that higher hardness deposition rate are obtained under the condition of power ratio is 1, working pressure 1.2 Pa, N2 partial pressure 0.3 Pa, rotating speed 2 m/s, deposition time 60 min, bias voltage 100 v. In addition, to grasp the intrinsic characteristics of deposition equipment is essential to the performance of the coating. Studying of the equipment sputtering pattern showed that it is ignorable that the deposition rate inhomogeneity of the target axial u and width direction v, while the opposite is true when consider the influence of the substrate-target distance on the coating deposition rate. The maximum deposition rate of the equipment was obtained when the substratetarget distance is 8mm.In situ diagnosis of plasma components in the process of composite coating preparation was employed by using mass spectrometry, it is shown that there were neutral particles, free radicals and ion in the vacuum plasma components, of which the former two were of the vast majority. Along with the change of the input ratio of co-sputtering power, particle composition and content of plasma components significantly changed, consequently coatings with different composition, structure and properties on the substrate surface were developed. The results of plasma mass spectrometry of components study also showed that Ti N*, CF2 * and CF *(including ionic and neutral particles and free radicals) were the main form of compound pattern in the reaction path of forming composite coating. Obvious hysteresis was manifested when Ti Nx was prepared by magnetron sputtering process, of which three kinds of states existed, named metal, transition and chemical mode. While hysteresis didn’t manifested itself during the process of preparing Ti Nx/CFy composite coating.The structure, wear resistance, anticorrosion properties of Ti Nx/CFy coating were characterized by a variety of testing technology and methods. The results show that there were predominant hard phase Ti Nx and soft phase CFy structure, of which C-N bond guaranteed good performance of the coating and made it compound. Power ratio is a key parameter to determine hardness, wettability, wear-resisting and corrosion resistance of the coating, The different proportion of CFy soft phase and Ti Nx hard phase in the preparation of the coating which was characterized by volume fraction was determined by the different power ratio. While the cosputtering RF power ratio between 0.33-3, named the volume fraction of Ti Nx between 0.72-0.12, the hardness of the composite coating was between 50 HV to 1500 HV, and the contact angle changed from 22.5 ° to 105 °. The increase of contact angle is due to the right amount composition of soft phase CF2- and- CF3 groups in the coating, which can improve the corrosion resistant ability and wear resistance ability at high humidity environment of the coating. Coatings of different wear and corrosion resistance can be prepared by regulate the process parameters of the preparation of the coating to obtain appropriate y value of soft phase CFy(i.e.,- CF2 and- CF3 groups content).Power ratio influence uniformity of the coating, the coating roughness increased when power ratio decreasing. Power ratio between 0.33 and 1 is more appropriate considering hardness and wear resistance of the coating, when TiNx phase distributed homogenously among CFy phase, and Ti Nx phase were connected with each other while rare large clumps of particles were observed; the performances of the coating were deteriorating when rotation speed > 2 m/s; Deposition time had little influence on the structure and chemical combination of the coating. Depth analysis indicates that polymer chain fragments tend to grow faster in the initial stage of deposition, that is to say, the polymer chain segment depth-first generated near the base material 65 Mn steel substrate. Nano indentation test of composite coating show that good abrasive wear resistance was obtained by power ratio of 1(volume fraction of 0.24: indicating the appropriate proportion between hard and soft phase), when furrow had not arisen; Wear volume test show that low wear volume of the composite coating Ti Nx/CFy was guaranteed when the power ratio were 0.43(volume fraction 0.43), 0.6(volume fraction 0.31) and 1(volume fraction 0.24), which was as low as the Al2O3 enhanced PTFE wear-resistant material’s. |
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