过共晶和亚共晶铝硅合金固—液复合铸造工艺的研究
发布时间:2018-05-13 12:53
本文选题:固-液复合 + 铝/铝复合 ; 参考:《吉林大学》2017年硕士论文
【摘要】:伴随着21世纪的步伐,世界的科学技术和工业生产都得到迅猛的突破和发展,由过共晶铝硅合金制造的缸套,可实现“全铝型发动机”的制备,有助于提高发动机的效率、延长使用寿命等,对汽车行业的发展、环境保护及节约能源等各个方面起着重要的作用。目前,各国对过共晶铝硅合金缸套材料的研究相对成熟,也不断加强对缸套/缸体总成一体技术的研发,但每种方法都相对复杂,并存在一定的问题。由于镶铸技术方法简单,对固态镶铸件没有大小、形状、尺寸及材质等要求,得到广泛的使用,本文为了更好地贴近实际生产,以最小的成本和资源达到最优的冶金结合,采用砂型铸造、重力浇注的方法,通过铝/铝固-液双金属复合成型工艺的实验,研究表面处理对铝/铝固-液双金属复合成型工艺的影响,即粗糙表面处理、光滑打磨处理、电镀锌处理、电镀镍处理、电镀铜处理对复合界面和组织的影响;以电镀铜为例,探讨了阴极电流密度对电镀层的影响、电镀时间与电镀层厚度的关系,并研究浇注温度、预热温度、电镀时间对双金属复合成形界面的影响。通过本文的研究,主要得出以下结论:1)表面粗糙、光滑处理无法使得铝/铝固-液双金属达到冶金结合,其根本原因是界面的氧化层阻碍双金属的润湿,而且在浇注过程中铝合金预制块表面会二次氧化,导致界面结合差。2)电镀锌、镍、铜处理均有助于固-液双金属的冶金结合,锌、镍、铜元素向两侧界面扩散,镍、铜在扩散过程中有聚集现象发生。在浇注温度750℃、电镀15min、预热温度为100℃条件下,相比于其他两种处理方法,电镀铜处理后铸件的剪切强度最高为23.45MPa,铜元素的扩散最远距离约为400μm。3)电流密度5A/dm2为最佳电流密度,电镀铜层表面平整良好、无毛刺和气泡等,电镀层质量与基体之间的结合符合电镀沉积标准。当电镀时间分别是5min、10min、15min时,获得实际的铜镀层厚度分别为是6.46μm、8.18μm、10.24μm。4)在浇注温度为780℃,电镀时间为10min,预热温度为100℃的条件下,可得最大的双金属复合界面剪切强度为28.23MPa,各参数对界面结合影响的主要次序是浇注温度、电镀时间、预热温度。过高的浇注温度会使预制块表面熔化加剧,甚至导致变形,经综合考虑,认为浇注温度为750℃,电镀时间为15min,预热温度为100℃,为最佳工艺参数。
[Abstract]:With the pace of the 21st century, the world's science and technology and industrial production have been a rapid breakthrough and development. The cylinder liner made of hypereutectic Al-Si alloy can realize the preparation of "all-aluminum engine" and help to improve the efficiency of the engine. Prolonging service life plays an important role in the development of automobile industry, environmental protection and energy conservation. At present, the research on hypereutectic Al-Si alloy cylinder liner materials is relatively mature, and the research and development of cylinder liner / cylinder block assembly technology has been strengthened, but each method is relatively complex, and there are some problems. Because of the simple technology and the lack of size, shape, size and material for solid castings, this paper aims to be more close to the actual production and to achieve the best metallurgical combination with the minimum cost and resources, in order to be more close to the actual production, and to achieve the best metallurgical combination with the minimum cost and resources. By means of sand mold casting and gravity casting, the effect of surface treatment on aluminum / aluminum solid liquid bimetallic composite molding process was studied through the experiments of aluminum / aluminum solid liquid bimetallic composite molding process, namely rough surface treatment, smooth grinding treatment, The effect of zinc plating, nickel plating and copper plating on the composite interface and structure was studied, and the effect of cathode current density on the electroplating layer, the relationship between plating time and the thickness of the plating layer, and the pouring temperature were studied, taking the electroplating copper as an example, the effect of cathodic current density on the electroplating layer was discussed. Effects of preheating temperature and electroplating time on bimetallic composite forming interface. Through the research in this paper, we can draw the following conclusion: 1) rough surface, smooth treatment can not make aluminum / aluminum solid liquid bimetallic metallurgical bonding, the basic reason is that the oxidation layer of interface hinders the wetting of bimetallic. Moreover, during the casting process, the surface of the prefabricated aluminum alloy will be reoxidized, resulting in the interface bonding difference. 2) the treatment of zinc, nickel and copper all contribute to the metallurgical bonding of solid liquid bimetallic, and the elements of zinc, nickel and copper diffuse to both sides of the interface. Copper aggregates in the diffusion process. Under the conditions of pouring temperature 750 鈩,
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