【作者】 吴彦西；

【导师】 王华昌；

【作者基本信息】 武汉理工大学 ， 材料加工工程， 2006， 硕士

【摘要】 国民经济的高速发展对模具工业提出了愈来愈高的要求,促使模具技术迅速发展,作为生产各种工业产品和民用产品的重要工艺装备,模具已发展成为一门产业。20世纪80年代以来,中国模具工业的发展十分迅速。近20年来,产值以每年15%左右的速度增长。2000年我国模具工业总产值已达280亿元人民币。 在现代生产中,模具是大批量生产各种制品的重要工艺装备,直接影响制品的质量和技术经济效益。随着科学技术的发展和市场竞争越来越激烈,对模具的性能要求越来越苛刻,寿命问题日益突出。表面强化技术作为提高模具使用性能和使用寿命的一种重要手段,在模具工业中占有十分重要的地位,得到了国内外的广泛重视。 TD法盐浴渗钒是TD法盐浴渗金属技术的一种,具有理论成熟,工艺稳定,处理效果好和价格低廉的特点。该工艺所形成的覆层在常温下具有良好的稳定性,具有优异的抗磨损能力,在冷作模具和零件的表面强化中应用效果良好。 TD法盐浴渗钒获得的覆层与基体结合力强于PVD、CVD等方法获得的结合力,覆层耐磨性能优异,但该法存在盐浴寿命不高、盐浴腐蚀严重、工件变形大以及表面粘盐清理困难等一系列难点,限制了该工艺在国内的推广应用。 本文对覆层反应的热力学、动力学、稀土催渗等相关理论进行了归纳与分析。在以前采用混合盐浴针对冷作模具钢进行TD处理所得出的结论的基础上,更深入的针对几种典型的冷挤压模具钢采用以硼砂为主要成分的酸性盐浴进行TD处理,比较同一种模具钢分别采用混合盐浴和酸性盐浴所得的覆层厚度和硬度等参数,分析盐浴成分对覆层硬度和厚度的影响。 试验用钢分别是Cr12MnV、T10、CrWMn、6W6Mo5Cr4V,所用盐浴是以硼砂为主要成分的酸性盐浴,主要考察碳含量对覆层厚度的影响。得出了覆层厚度与含碳量;覆层厚度与盐浴处理时间等因素间的对应关系。其中6W6Mo5Cr4V钢的碳含量为0.55～0.65,碳含量较低,又含有大量强碳化物W、Mo、V,这些强碳化物形成元素将基体中的碳固定下来,影响覆层的成长。所以,对6W6Mo5Cr4V钢进行分组,一组未经过渗碳,一组经过3小时渗碳,比较渗碳和未渗碳的覆层厚度及硬度性能,为TD处理在低碳高合金钢的应用提供参考依据。应用SEM和显微硬度计对覆层的金相和显微硬度进行了观察和测定。采用电子探针更多还原

【Abstract】 The rapid development of the national economy made mould industry rising demand,prompt mould techonology rapid development,mould is the important instrument to the each product of industrial and domestic,mould have become a very important industry. Since the beginning of the 1980s, the development of china’s mould industry is very rapid. Over the past 20 years, Output of mould industry grow at an annual rate of around 15%.China’s mould industrial output value in 2000 reached 28 billion yuan.Moulds are important equipments in mass production of all kinds of product in modern industry. The quality of moulds is a key factor which influences the quality and economic benefits of products. As the development of the industry, the requirement of the performance of moulds becomes higher and higher. The mechanical properties and the service life of moulds can be improved largely by appropriate application of the surface strengthening technique. Thus the surface strengthening technique plays a very important role in the mould industry, and attracts widely attentions.Salt-bath vanadising by TD method(thermal diffusion) belongs to the TD method. The coating formed by this process is very stable at room temperature. The coating shows good wear property. And high service life obtained in applying to cold work die.The bonding strength of the coating formed by this process is also much higher than which formed by PVD or CVD process. But this method has some limitations such as the very short service life, hard corrosion of salt-bath, large deformation of work piece and bad surface finish. So this process has not been used widely at china.Theories concerning the probability and the velocity of coating reaction were studied in this paper. On the basis of conclusion of previous experiment that mixed salt bath vanadinizing to the cold die, use the acid borax salt of bath in the TD process to several typical cold steel, compared the thickness ,hardness and other parameters that the same steel use the mixed salt of bath and the acid borax salt of bath,analysis the components of the salt of bath’s impact to the coating’s hardness andthickness.The steel used in this experiment incloudCrl2MnV, TICK CrWMru 6W6Mo5Cr4V. Use the acid borax salt of bath in this experiment. The aim is research the relation between coating thickness and carbon content and holding time. 6W6Mo5Cr4V is Low -carbon alloyed steel,theelment W, Mo, V is Strong carbide, these elments will Influence coating’s growth. So use the process carbonization to part of 6W6Mo5Cr4V Research the coating’s thickness and hardness between the 6W6Mo5Cr4V have used theprocess carbonization and no by the acid borax salt of bath.Use the SEM observe the metallographic,Use the Micro sclerometer measure the hardness of the coating. Use the electron probe micro-analysis(EMPA) analysis the element and content.The coating formed by TD method has many advantages, such as compact coating, uniform thickness, very high hardness, good bonding strength and power saving property. This technology has obtained the anticipated target in the experimental stage.更多还原