【作者】 赵正；

【导师】 刘福田；

【作者基本信息】 济南大学 ， 材料学， 2008， 硕士

【摘要】 本论文将钢结硬质合金的优异性能赋予钢基体表面,获得了具有高硬度、高耐磨性与高耐腐蚀性能且界面结合优异的钢结硬质合金覆层材料。研究了B和Mo的掺入对钢结硬质合金覆层烧结温度、力学性能、物相组成以及微观结构的影响,并将其应用于机械零件表面改性,获得了较好的效果。本研究在钢基体表面制备了M、3B、4B、5B、3BMo五类钢结硬质合金覆层材料。确定了硬质相和粘结相的体积分数,B、Mo等合金组分添加量以及粘结剂PVB的添加量。确定了制备钢结硬质合金覆层材料的工艺流程,主要包括成形料浆的制备工艺、钢基体的处理、覆层坯体的成形工艺与覆层材料的烧结工艺等四大部分。确定了覆层材料的烧结工艺制度。烧结真空度为1.0×10-2～1.0×10-3Pa;烧结温度制度为:以10℃/min从室温加热至400℃保温30min,继续以10℃/min加热至1000℃保温30min,然后以5℃/min的速度升温至最高烧结温度保温30min,再随炉自然冷却。通过烧结实验确定了各体系覆层材料的烧结温度,并分析了B和Mo的添加对覆层材料烧结温度的影响。结果表明,B添加后,有效的降低了覆层材料的烧结温度,3B覆层材料的烧结温度相比M覆层材料的烧结温度降低50℃。随着B质量分数的增加,烧结温度有所提高。在3B覆层配料基础上添加Mo,覆层材料的烧结温度相对Mo添加前升高25℃。研究了钢结硬质合金覆层材料的硬度、弯曲强度等力学性能,分析了B和Mo的添加对覆层材料力学性能的影响。结果表明,B添加后,覆层材料无论是洛氏硬度还是维氏硬度都有所提高,洛氏硬度可提高2HRA,维氏硬度提高28.38 Kgf/mm2。随着B质量分数的增加,覆层硬度进一步提高。在3B覆层配料基础上添加Mo后,3BMo覆层的洛氏硬度相对3B覆层提高1.4HRA,维氏硬度提高17.67Kgf/mm2。覆层受压应力或受张应力时,B的加入均降低了覆层材料弯曲强度,但随B含量的增加而降低。无论覆层受压应力还是受张应力,添加Mo的3BMo覆层材料的弯曲强度相对Mo未添加的3B覆层材料的弯曲强度有所提高,覆层受压应力时提高237.47 MPa,覆层受压应力时提高237.10MPa。采用干摩擦磨损与冲蚀磨损两种方式研究了钢结硬质合金覆层材料的摩擦磨损性能。结果表明,与M覆层材料比较,添加B和Mo后的覆层材料的耐磨性均有不同程度的提高。研究了覆层材料的耐腐蚀性能,结果表明,钢结硬质合金覆层具有比钢基体更优越的耐腐蚀性能。研究了钢结硬质合金覆层材料中的物相组成、硬质相与粘结相的分布状态以及覆层与基体的界面结合特征。分析了覆层材料扩散界面区域的范围,并通过线扫描照片结合覆层/钢基体结合界面显微硬度的测试分析了界面过渡区的形成机理。B和Mo添加后有Fe2B和Mo2FeB2等新相生成。B的添加使覆层和钢基体之间形成了具有冶金镶嵌结构的过渡层。初步将钢结硬质合金覆层复合于易磨易蚀的机械零件表面,成功制备了部分钢结硬质合金覆层零件。试验证明,覆层处理大大延长了覆层零件的使用寿命。更多还原

【Abstract】 In this thesis, a novel kind of steel bond hard alloy cladding materials with outstanding hardness, excellent wear and corrosion resistance and high cladding/substrate bonding strength was developed by vacuum liquid phase sintering technique, and the influence of B and Mo on the performance of the steel bond hard alloy cladding materials was studied. The cladding material was applied in the surface of the machine accessories, and good effects were obtained.Five types of cladding materials have been developed successfully on the sides of steel for the first time, which were designated M, 3B, 4B, 5B and 3BMo respectively. The basic volume fraction of hard phase and binder phase, the contents of alloy elements B and Mo, and the adhesive PVB in claddings were determined.The technology process of the preparation of the cladding materials were established, which included four parts: the technology of the preparation of the slurry; disposal technology of the steel substrate; molding mode of the cladding formation and the sintering technology of the cladding materials.The liquid phase sintering technique was used for sintering of cladding materials. During sintering, the vacuum in furnace keeps 10×10-2～10×10-3Pa, The temperature is elevated from room temperature to 400℃at a speed of 10℃/min, and holds for 30 min, After that , the temperature is raised to sintering temperature, and holds for 30 min, the temperature is further elevated to 1000℃at a speed of 5℃/min, and holds for 30min. Finally, the samples are cooled in the furnace naturally. The elevated rate of temperature is 5℃/ min.The sintering temperature of five types cladding materials was determined, and the influence of the B and Mo on sintering temperature was analyzed. The results indicated that the sintering temperature of cladding material was almost 50℃lowered compared with that without B and heightened as more and more B added. When Mo was added on the base of B, the sintering temperature of cladding material was 25℃higher compared with that without Mo. The mechanical properties of the steel bond hard alloy cladding materials such as hardness and bending strength were investigated. The effects of B and Mo on hardness and bending strength were investigated in detail. The Rockwell hardness and Vickers hardness of cladding materials containing B were both higher than that of cladding material M without B and the hardness kept increasing with more and more B containing in the cladding, and the Rockwell hardness was 2HRA higher and Vickers hardness was 28.38 Kgf/mm2 higher. The Rockwell hardness of cladding material 3BMo was 1.4HRA higher than that of 3B and the Vickers hardness was 17.67Kgf/mm2 higher than that of 3B. The results of three-point bending method indicated that the bending strengths of the cladding materials endured compressive stress and tensile stress respectively were improved after B was added, however, the bending strength reduced with the content of B increasing. The adding of Mo in the cladding could heighten the bending strength markedly.The wear resistance of the steel bond hard alloy cladding materials was studied by dry friction method and erosion wear method. The results indicated that the wear resistance of cladding material 3B, 4B, 5B and 3BMo was improved reasonably compared with the cladding material M without B and Mo. The corrosion resistance of the steel bond hard alloy cladding material was investigated and from the results of that, the corrosion resistance of the cladding materials was better than Q235 steel.The phase composition of the steel bond hard alloy claddings and the distribution of the hard phase and binder phase were studied. The interface character between hard phase and binder phase and the interface character between the cladding and the steel substrate were both investigated. The compartmentalization of the diffuse interface layer between steel and cladding material was advanced. The formation mechanism of the interface layer was investigated by the line scan analysis and the micro-hardness testing on the interface of cladding and steel. There were new phase Fe2B and Mo2FeB2 produced after B and Mo added. A metallurgical inlaying structure without cavity or gap formed between the cladding and the steel substrate because of B. The operational life of cladded hardware was much longer than that of uncladded hardware.The steel bond hard alloy cladding material was applied on the surfaces of the facile abrasion and erodible mechanical accessories, and some cladding hardwares were fabricated successfully. The working condition of steel bond hard alloy cladding hardwares under practical working condition was studied.更多还原