自蔓延高温合成技术制备新型金刚石磨头及其加工性能研究

发布时间：2018-03-21 08:49

本文选题：自蔓延　切入点：雕刻磨头　出处：《南京航空航天大学》2017年硕士论文　论文类型：学位论文

【摘要】：自蔓延高温合成法是利用原料间的高放热化学反应生成新材料的一项技术,试样经外部热源引燃后产生燃烧波并迅速传播至整个样品,该技术具有工艺简单、反应时间短、产物污染少等特点。针对传统烧结金刚石雕刻磨头磨粒易脱落、把持强度较低等缺点,本文提出应用自蔓延高温合成技术制备新型金刚石雕刻磨头,利用高频感应加热引燃压坯自蔓延反应。分析节块自蔓延反应过程特征,优化结合剂配比和制作工艺;分析反应后磨粒和胎体断面微观形貌,研究金刚石和自蔓延反应的相互影响及磨粒-胎体间的界面结合。通过加工性能试验验证该雕刻磨头性能。本文完成的主要工作有:(1)设计并制作了磨头压坯模具,搭建高频感应机引燃平台;磨头胎体选取为添加金属Ni的铜基结合剂,利用铝钛自蔓延反应制备了多层金刚石雕刻磨头;热力学计算表明金属Ni的加入有利于提高该体系的绝热温度,促进自蔓延反应的进行。(2)分别分析压坯成型密度、压坯中反应物Al-Ti的含量、金属Ni的含量对体系自蔓延过程特征的影响。试验表明反应时压坯中液相的流动是胎体孔隙形成的主要原因;原料中不参与反应的惰性物质构成节块的骨架,反应物过多会导致骨架失稳坍塌,合适的Al-Ti含量应在25%wt以下。(3)压坯中引入金刚石会降低燃烧波传播速度并增大孔隙率。使用现代理化分析手段研究金刚石-胎体结合区域,发现元素Ti在过渡区存在偏析;磨粒表面附着物的定点能谱分析表明其主要金属成分为Ti,可以认为结合区域中磨粒与胎体发生了化学冶金结合;由于自蔓延反应温度很高,反应后金刚石磨粒力学性能有所下降,Ni含量的增加会加剧金刚石石墨化程度。(4)对制备的两组不同金属组分的自蔓延雕刻磨头和普通烧结雕刻磨头进行加工性能试验,并分析加工中磨粒磨损过程。对比试验表明自蔓延雕刻磨头的加工性能优于普通烧结磨头;Al-Ti含量为25%wt的自蔓延磨头最为锋利,但胎体耐磨性不及Al-Ti含量为15%wt的磨头;磨粒磨损分析表明自蔓延反应后结合剂对金刚石把持力较高,磨粒利用率提高。
[Abstract]:Self-propagating high temperature synthesis (SHS) is a technique for producing new materials by high exothermic chemical reaction between raw materials. The combustion wave of the sample is produced after ignition by external heat source and propagates rapidly to the whole sample. The technology is simple and the reaction time is short. In view of the disadvantages of the traditional sintered diamond engraving abrasive head, such as easy to fall off, low holding strength and so on, a new diamond engraving abrasive head was prepared by using self-propagating high temperature synthesis technology. Self-propagating reaction of combustible billet was induced by high-frequency induction heating. The characteristics of self-propagating reaction process of knots were analyzed, the proportion of binder was optimized and the fabrication process was optimized. The interaction between diamond and self-propagating reaction and the interfacial bonding between abrasive particle and matrix are studied. The performance of the engraved abrasive head is verified by processing performance test. The main work accomplished in this paper is to design and manufacture the grinding head pressing die. The igniting platform of high frequency induction machine was set up, the matrix of grinding head was selected as copper based bond added with metal Ni, and the multi-layer diamond engraving grinding head was prepared by Al-Ti self-propagating reaction. The thermodynamic calculation shows that the addition of Ni can improve the adiabatic temperature of the system and promote the self-propagating reaction to analyze the compaction density and the content of reactant Al-Ti in the compacts, respectively. The effect of Ni content on the characteristics of self-propagating process shows that the liquid phase flow in the compacts is the main reason for the formation of pore in the matrix, and the inert material in the raw material does not take part in the reaction to form the skeleton of the node block. Too many reactants will lead to the collapse of skeleton instability. The suitable Al-Ti content should be below 25wt. The introduction of diamond into the compacts will reduce the velocity of combustion wave propagation and increase the porosity. The modern physicochemical analysis is used to study the diamond matrix binding region. It is found that the element Ti is segregated in the transition region, and the fixed point energy spectrum analysis of the surface attachment of abrasive particles shows that the main metal component is Ti, which can be considered as the chemical metallurgical bonding between the abrasive particles and the matrix in the binding region, due to the high temperature of the self-propagating reaction. When the mechanical properties of diamond grains decrease after reaction, the increase of Ni content will increase the degree of graphitization of diamond. (4) the processing performance tests of two groups of self-propagating engraving grinding heads with different metal components and common sintered engraving abrasives are carried out. The comparative tests show that the self-propagating engraving grinding head has better processing performance than that of the normal sintered grinding head with 25wt Al-Ti content, but the wear resistance of the matrix is not as good as that of the 15wt Al-Ti grinding head. The abrasive wear analysis shows that the holding force of the binder to diamond is higher and the utilization ratio of abrasive particles is higher after the self-propagating reaction.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG731

【参考文献】