【作者】 徐德生；

【导师】 任露泉；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2004， 博士

【摘要】 磨料磨损是矿山、工程和农业机械等地面机械触土部件磨损件失效的主要原因。提高地面机械部件的耐磨性能方法除研究开发新型抗磨损材料、添加润滑材料和从结构上进行合理的设计外，表面硬化（表面改性）则是提高地面机械部件质量、延长使用寿命、改善使用性能的重要方法。目前，常用的表面硬化技术有化学、物理、激光、电子束热处理、喷涂、沉积、镀层等。这些方法绝大多数是对整个表面进行处理，且硬化层厚度较薄，往往在服役中很快被磨损掉，失去对机械部件本身的保护作用，降低了机械部件在各种工况条件下使用的有效性。因此，探索新的抗磨材料和机理，以便能更有效地提高地面机械触土部件的使用寿命。传统的观念都是将追求提高磨损部件的表面光滑度作为提高其耐磨性能的必要手段，而依据仿生研究结果，非光滑表面具有减粘、降阻、耐磨作用。在此设计思想指导下，本文模仿蜣螂头部体表非光滑特征，对钎焊耐磨复合涂层进行了仿生设计，首次以快速高效的钎焊方法制备了以铜基钎料合金为基体的仿生非光滑耐磨复合涂层；系统研究了仿生非光滑钎焊耐磨复合涂层制备工艺、孔隙度、力学性能、耐磨性能、组织结构与抗磨机理；并研制了适合仿生非光滑复合涂层制备的高性能多元铜基钎料，确定了复合涂层的较佳组分配比。所研制的仿生非光滑复合涂层具有优良的力学性能和高的耐磨料磨损性能。研究工作拓展了仿生材料研究领域，为提高地面机械触土部件等易磨损件的抗磨性开辟了一条新途径。以典型土壤动物—蜣螂头部体表非光滑单元体的统计分析为基础，建立典型土壤动物—蜣螂体表非光滑单元体的数学描述式，确定数学描述式中参数的取值区间，利用演化计算中的遗传算法和演化策略，建立起典型土壤动物非光滑体表的数学模型。根据工程仿生学原理，借鉴功能复合材料的设计思想，依据典型土壤动物—蜣螂头部非光滑体表的数学描述式，对钎焊耐磨复合涂层进行了仿生设计，确定了适合仿生非光滑钎焊耐磨复合涂层的非光滑表面参数—凸包顶点间距与凸包高度的比例，给出了制备仿生非光滑WC/Cu复合涂层的增<WP=128>强硬质颗粒相WC的含量范围（44~84wt%）。通过对复合涂层钎焊成形质量的研究确定了合适的工艺参数，在此基础上系统研究了仿生非光滑耐磨复合涂层的密度、孔隙度、耐磨性，研究结果表明：钎焊方法、钎料、钎剂、硬质点颗粒大小与含量等对非光滑耐磨复合层的成形、孔隙度与密度、耐磨性能有重要影响。用高频钎焊方法制备的仿生非光滑耐磨复合涂层耐磨性能明显优于炉中钎焊方法制备的复合涂层；硬质点颗粒WC含量和粒度是决定复合涂层表面非光滑尺寸参数的主要因素，WC含量过低或过高均不能发挥出复合涂层的耐磨性优势，随WC含量增加，复合涂层磨损量减少，相对耐磨性提高，当WC含量ΦW增为50~60wt%时相对耐磨性最高，增强硬质相WC颗粒在涂层中分布均匀，涂层表面非光滑节点—凸包顶点间距与凸包高度的比例c/h计算值为2.37~2.57，实际值为2.48~2.68；选用BCu60Zn钎料、60/80目（平均尺寸210μm）或40/60目（平均尺寸300μm）WC颗粒、含量为50~60wt%、钎剂含量为1~3wt%，通过高频钎焊工艺在碳钢表面制备的非光滑耐磨复合涂层密度高、孔隙度低、耐磨性高。60/80目WC、ΦW为50wt%的复合涂层，实际c/h为2.68，接近由蜣螂体表非光滑结构数学模型确定的c/h值，在两体静载磨料磨损工况下，其耐磨性是45钢（淬火态）的11.9倍，是高铬铸铁的4.7倍。研究了工况条件对仿生非光滑复合涂层耐磨性能的影响规律，结果表明：当载荷小于0.354MPa时, 随载荷增加复合涂层磨损量显著增加，载荷超过0.354MPa后，磨损量增加趋势变缓，且基本上为直线关系，此时复合涂层相对（高铬铸铁）耐磨性基本不变，近似为一常数5.08；随磨粒尺寸增大（目数降低）复合涂层磨损量增加，相对（高铬铸铁）耐磨性降低。磨粒粒度在80目附近有一临界尺寸，试验条件下该临界尺寸约为175μm，超过临界磨粒尺寸，磨粒尺寸增加复合材料磨损量急据增大。研究了复合涂层自身强度及其与被强化基体（碳钢）结合强度与WC颗粒粒度和含量的关系，结果表明：在含量为30~60wt%时，WC颗粒粒度对复合涂层自身强度有明显影响，随颗粒尺寸减小复合涂层强度明显提高，而在WC含量过低或过高时，粒度对复合涂层自身强度的影响无明显规律。80/200目（平均尺寸120μm）、60/80目WC颗粒增强涂层强度明显比40/60目WC颗粒增强涂层强度高；随WC含量增加，三种不同粒度WC颗粒增强复合涂层自身强度逐渐降低，在WC含量为30 wt%时达到一个低谷，继续增加WC含量复合涂层强<WP=129>度则升高，当WC含量为40~50wt%时复合涂层强度达到一个局部峰值，80/200目、60/80目、40/60目WC颗粒增强复合涂层强度分别为112MPa、100 MPa、60 MPa；复合涂层与碳钢基体结合强度均高于涂层自身强度，在WC含量为50wt%时结合强度达到局部峰值，此时WC粒度对其无明显影响；80/200目、60/80目、40/60目WC复合涂层与碳钢基体结合强度分别为152MPa、160 MPa、156 Mpa。研究揭示，提高铜锌钎料对WC和钢的润湿性能，将提高非光滑耐磨复合层的耐磨性能。为进一步提高铜锌钎料对WC和钢的润湿性能和填更多还原

【Abstract】 Abrasive wear is one of main reasons that brings about the soil-engaging components of terrain machines such as mining, engineering, agricultural machines and so on to lose efficacy. In addition to developing new type wear-resistant materials, adding lubricant materials and designing rationally for the structures, surface hardening technologies for the soil-engaging components of terrain machines are the significant methods that can improve quality and wear resistance of the components and prolong their service life. Up till now, the surface hardening technologies in common use are a variety of treatment technologies including chemistry, physics, laser and electron beam and bead welding, spraying, depositing, plating and so on. The whole surfaces are treated using technologies usually and the costs are higher, but the thickness of hardening coating is thinner and worn quickly on an extended term of service that loses their protective coating and reduces effectiveness of the machine components in using. Moreover, raising surface hardness of engineering materials is limited. Consequently, developing new-type wear-resistant materials and mechanisms would improve service life of the soil-engaging components of terrain machines effectively. Traditional concepts seek surface lubricity as necessary conditions that improve wear resistance of the machine components.Bionic Research results show that non-smooth surface can reduce adhesion and resistance of materials and improve wear-resistant performance that give birth to designing idea of the wear-resistant composite coating with bionic non-smooth surface. Based statistical analysis on geometrical morphologies of most soil animal body surface, a <WP=131>mathematic description formula is set up for the non-smooth surface of typical soil animal body. Limits of numerical value of mathematic description formula are ascertained and the mathematic model is set up using arithmetic operation and genetic algorithm. Aim of this work offer theoretical bases to study composite coating with bionic non-smooth surface. Brazing reinforced particles to steel surface using filler metals, a composite coating with bionic non-smooth surface in thickness from tens microns to tens millimeter is formed. The brazing technology is used to manufacture composite coating with bionic non-smooth surface that possesses the characteristics of simple technics, convenient operation, lower cost and credible performance.Results show that the brazing methods, flux, wettability of filler metal to reinforced particles and to steel surface, size and weight percent of reinforced particles have significant influences on the molding, porosity, density and wear resistance of the composite coating with bionic non-smooth surface. The wear resistance of the composite coating with bionic non-smooth surface using high frequency induce brazing exceed that of furnace brazing. Porosity and density represents the close-grained measurement, compactness and wear resistance of the composite coating directly. The Cu-Zn filler metal (BCu60Zn) has lower price and melting point, good anti-erosion and wettability and filling up vacancy to reinforced particles and steel surface. BCu60Zn filler metal is processed to powder in granularity of 175~246μm and mixed with carbide tungsten and flux in weight percent of 50 and 1-3, respectively. A composite coating with bionic non-smooth surface is formed using high frequency induce brazing on the steel surface. The structures of composite coating are compact, its porosity is lower and density is high. Under the condition of two bodies abrasive-wear, the wear resistance of composite coating with bionic non-smooth surface is 11.9 and 4.7 times as much as that of 45# steel (quench-hardening) and high chrome cast iron respectively.The influences of service conditions on the wear resistance of the composite coating with bionic non-smooth surface are studied. The results show, with <WP=132>increasing the loading, the wearing capacity of the composite coating is greatly enhanced when load更多还原