【作者】 梁云虹；

【导师】 姜启川；

【作者基本信息】 吉林大学 ， 材料加工工程， 2008， 博士

【摘要】 本文通过研究Cu-Ti-C和Cu-Ti-B₄C体系在钢液外的CS反应行为和机制,优化出钢液内CS反应工艺参数,采用CS反应技术与铸造法相结合,成功地制备出TiC和TiC-TiB₂颗粒局部增强钢基复合材料。因此,本文以Cu-Ti-C和Cu-Ti-B₄C体系为研究对象,研究动力学影响因素对DTA、SHS和TE反应动力学的影响规律,揭示三种反应条件下的反应机制和其共性规律,为研究钢液内CS反应行为和制备组织健全、性能优异的TiC和TiC-TiB₂颗粒局部增强钢基复合材料奠定理论基础。提出了Cu-Ti-C和Cu-Ti-B₄C体系在DTA、SHS和TE反应条件下反应机制均为溶解反应析出机制,并揭示出其共性规律,即Cu与Ti首先固相扩散反应形成TixCuy金属间化合物,随后形成Cu-Ti液相,C或BB₄C颗粒溶解到Cu-Ti液相中,形成Cu-Ti-C三元液相或Cu-Ti-B-C四元液相,当液相中[Ti]、[C]、[B]的浓度达到形成TiC或TiC与TiB₂的热力学条件后,反应析出TiC或TiC与TiB₂。揭示出动力学影响因素（Cu含量、Ti、C和BB₄C粉粒度）对DTA、SHS和TE反应动力学的影响规律,Cu含量不仅影响固相反应形成TixCuy的动力学条件,而且影响反应形成的陶瓷相数量,即影响体系放热量,因此,随着Cu含量增加,产物中TiC和TiB₂颗粒尺寸逐渐减小,燃烧温度和燃烧波速逐渐下降,引燃时间先降低后增加,Cu含量为20wt.%时引燃时间最短;Ti粉粒度仅影响固相反应形成TixCuy的动力学条件,即反应速率,因此,仅对引燃时间有影响,随着Ti粉粒度增加,引燃时间延长,对燃烧温度、燃烧波速、陶瓷颗粒尺寸和形貌影响不大;C和B₄BC粒度影响Cu-Ti-C三元液相或Cu-Ti-B-C四元液相的形成速率,即影响反应析出陶瓷颗粒的速率,因此,随着C或BB₄C粉粒度增加,产物中TiC和TiB₂颗粒尺寸逐渐减小,燃烧温度和燃烧波速逐渐下降,引燃时间逐渐增加,反应越来越难以进行。采用Cu-Ti-C和Cu-Ti-B₄C体系钢液外CS反应优化出的工艺参数,通过CS反应技术与铸造法相结合,成功地制备出TiC和TiC-TiB₂颗粒局部增强钢基复合材料,增强区内TiC和TiB₂陶瓷颗粒尺寸细小,分布均匀,组织致密,界面干净,增强区域和基体区域之间的过渡区域结合良好;增强区的硬度和耐磨性明显高于基体区,其中,TiC-TiB₂双相陶瓷颗粒局部增强钢基复合材料增强区的硬度和耐磨性明显高于TiC单相陶瓷颗粒局部增强钢基复合材料增强区的硬度和耐磨性;同时,优化出硬度与耐磨性综合性能较佳的CS反应工艺参数。发现反应动力学影响因素（Cu含量、C、BB₄C粉粒度）对Cu-Ti-C和Cu-Ti-B₄C体系钢液内外CS反应动力学（引燃过程、燃烧温度、产物尺寸和形貌等）的影响规律是基本一致的,其差别仅是反应速度与程度不同。更多还原

【Abstract】 Particle reinforced metal matrix composites（MMCs） combine high strength, high stiffness and high wear-resistance of the reinforcement with high ductibility and high toughness of the metal matrix, and provide excellent combination properties of strength and toughness that traditional single materials is absence, which solve preferably the contradiction of hardness and toughness, therefore, this kind of material has gained extensive application. But, However, all the progressed composites are monolithic composites, in many practical occasion, the monolithic composites reinfoced with particulates are no demand, and the abrasion of components often occur in local area, and the other part of components require excellent obdurability, Hence, in the present work, our group highlights and applies a new and potential process in which CS plus traditional casting techniques produce successfully ceramic particulate locally reinforced steel matrix composites, that is, the local easily wear region of wear casting is locally reinforced by ceramic particulates. However, it is difficult to directly research CS reaction in the steel liquid, thus, in the present work, Cu-Ti-C and Cu-Ti-B₄C systems is selected as the subject of study, and the effect of kinetic impact factor on the DTA、SHS and TE reaction is researched, and reveals the reaction mechanism and common rule of these three reactions. Based on these research results, the optimal processing parameter of CS reaction is optimized for the study of CS reaction behavior in steel liquid and the fabrication of TiC and TiC-TiBB₂ particulates locally reinforced steel matrix composites with healthy microstructure and excellent properties. The reaction process of CS in the melt is researed, and by making full use of and exerting the academic advantage of the two kind of techniques, the microstructure and properties of TiC and TiC-TiB₂ Bparticulates locally reinforced steel matrix composites is controlled reasonablly.The main research results of the present study are as follows: 1) The reaction path of ceramics formation in the Cu-Ti-C and Cu-Ti-B₄C systems under the DTA conditions and the common regularity in these two systems are given as follows:In the Cu-Ti-C and Cu-Ti-B₄C systems, TixCuy compounds （x and y depending on the Cu content） were firstly formed due to the solid diffusion between Ti and Cu; and subsequently, the Cu-Ti liquid were formed at an eutectic temperature or melting temperature with the increase of temperature, and simultaneously these liquid spreaded on the surface of C or B₄C particles; and then some C and B atoms can dissolve into the liquid to form Cu-Ti-C liquid or Cu-Ti-B-C liquid, and some TiC or TiC and TiB₂ B can be formed firstly at the locations where [C] and [B] are relatively high; with the further increase of temperature, the TixCuy compounds melt to form Cu-Ti liquid, and then more C and B atoms can dissolve into the liquid to form a large amounts of Cu-Ti-C liquid and Cu-Ti-B-C liquid, and many TiC or TiC and TiBB₂ particulates were precipitated from the liquid and grow up.2) The reaction mechanism of ceramics formation in the Cu-Ti-C and Cu-Ti-B₄C systems during SHS reaction and the common regularity in these two systems are given as follows:a) In the Cu-Ti-C system, the SHS process can be described as follows: Cu+Ti+C→TixCuy+Cu+Ti+C→Cu-Ti （liquid phase）+Ti+C→Cu-Ti-C （liquid phase）+TiC+C→TiC+Cu, the TixCuy depends on the Cu content. The SHS mechanism can be described to be dossolution -precipitation mechanism, namely, TixCuy compounds were firstly formed due to the solid diffusion between Ti and Cu; and subsequently, the Cu-Ti liquid were formed at an eutectic temperature or melting temperature with the increase of temperature, and then some C atoms can dissolve into the liquid to form Cu-Ti-C liquid, and some TiC can be formed firstly at the locations where [C] was relatively high; with the further increase of temperature, the TixCuy compounds melt to form Cu-Ti liquid, and then more C atoms can dissolve into the liquid to form a large amounts of Cu-Ti-C liquid, and many TiC particulates were precipitated from the liquid; finally, the reaction can not continue until all the C particles were consumed completely.b) In the Cu-Ti-B₄C system, the SHS process can be described as follows: Cu+Ti+B₄C→TixCuy+Cu+Ti+B₄C→Cu-Ti （liquid phase）+B₄C→Cu-Ti-B （low concentration）-C （liquid phase）+TiC+B₄C→Cu-Ti-B （high concent- ration）-C（liquid phase）+TiC+TiBB₂+B₄C→TiB₂+TiC+Cu; the TixCuy depended on the Cu content while that of TixBy depended on the concentration of C and B in the liquid. The SHS mechanism can be described to be dossolution -precipitation mechanism, namely, TixCuy compounds were firstly formed due to the solid diffusion between Ti and Cu; and subsequently, the Cu-Ti liquid were formed at an eutectic temperature or melting temperature with the increase of temperature, and simultaneously these liquid spread on the surface of B₄C particles; and then some C atoms escaped from B₄C particles can dissolve into the liquid to form Cu-Ti-C liquid, and some TiC can be formed firstly at the locations where [C] was relatively high; therefore, TiC formed earlier than TiB₂Subsequently, with the continuous escape and dissolution of C and B, a large amounts of Cu-Ti-B-C liquid were formed and many TiC and TiB₂ particulates were precipitated from the liquid.c) During the SHS process form the Cu-Ti-C and Cu-Ti-B₄C systems, a common regularity is given: TixCuy compounds were firstly formed due to the solid diffusion between Ti and Cu; and subsequently, the Cu-Ti liquid were formed at an eutectic temperature or melting temperature with the increase of temperature, and simultaneously these liquid spread on the surface of C or B₄C particles. Some C and B atoms from B₄C particles can dissolve into the liquid to form Cu-Ti-C and Cu-Ti-B-C liquids, and ceramics particulates can be formed. The SHS reaction begined with the formation of liquid. Compared with the process in the DTA apparatus, for the same system, the SHS reaction can be initiated without many intermediate reactions once the liquid were formed.3) The effect of kinetic impact factor on the SHS reaction kinetics of Cu-Ti-C and Cu-Ti-B₄C systems is revealed: with the increase of Cu content, the combustion temperature and wave velocity decreased while the ignition time exhibited a first increase and then a significant decrease with the minimum value at 20wt.%. Moreover, the ceramic particulates size decreased with the increase of Cu content; With the increase of C and B₄C particle sizes, the reaction became difficult to ignite and the combustion temperature and wave velocity decreased. Furthermore, the reaction became incomplete and the ceramic particulates sizes became smaller with the increase of C and B₄C particle sizes. Compared with the C and B₄C particle sizes, Ti particle sizes exhibited a slight influence.4) The effect of kinetic impact factor on the TE reaction kinetics of Cu-Ti-C and Cu-Ti-B₄C systems is revealed: with the increase of Cu content, the combustion temperature decreased while the ignition temperature increased; Moreover, the ceramic particulates size decreased with the increase of Cu content; With the increase of C and B₄C particle sizes, the combustion temperature decreased while the ignition temperature increased and the reaction became incomplete. Furthermore, the ceramic particulates sizes became smaller with the increase of C and B₄C particle sizes. Compared with the C and B₄C particle sizes, Ti particle sizes exhibited a slight influence. Compared with the DTA and SHS process, the heat from the pre-reaction can increase the temperature to the ignition temperature. Therefore, the formation of liquid was later than the ignition reaction.5) Using the optimized processing parameter of CS reaction of Cu-Ti-C and Cu-Ti-B₄C systems outside steel liquid, TiC and TiC-TiB₂ particulates locally reinforced steel matrix composites are successfully fabricated by CS reaction and casting techniques. The sizes of TiC and TiB₂ Bparticulates in reinfoced region are fine, and their distribution is relatively uniform, and the interface between the reinforcement and matrix is clean, and the bonding of transition region between reinforce and matrix area is good; compared with the matrix region, the hardness values of the reinforced region of two systems are increased about 1.3².4 times, and the wear resistance is increased 1.1³.1 and 1.7³.2 times; however, with increasing Cu content, the wear resistance of the composite is increased firstly and then decreased. The hardness and wear resistance of the reinforced region of TiC-TiB₂ particulates locally reinforced steel matrix composites are higher obviously than those of TiC particulate locally reinforced steel matrix composite; meanwhile, the optimal processing parameter of CS reaction with hardness and wear resistance is optimized. In the Cu-Ti-C system, Cu contents 30⁴0wt.%, Cu particle size ⁶μm, Ti particle size ²5μm, C particle size ¹μm^<sup>38μm; In the Cu-Ti-B₄C system, Cu contents 31⁴0wt.%, Cu particle size ³μm, Ti particle size ³8μm, B₄C particle size³.5μm^<sup>45μm.6) It is found that the influencing law of the impact factor of reaction kinetics （Cu content, C, granularity of B₄C powder） on DTA, SHS, TE and CS reaction kinetics （igniting process, combustion temperature, the size and morphology of product） of Cu-Ti-C and Cu-Ti-B₄C systems outside steel liquid is coincident, their differences only lie in different reaction velocity and digree.更多还原