【摘要】：工業(yè)的快速發(fā)展使得以碳鋼、不銹鋼、合金鋼等為主要材料制造的結(jié)構(gòu)零部件使用的領(lǐng)域越來越廣泛,環(huán)境越來越復(fù)雜,這通常需要材料具有較好的表面性能,例如耐磨耐腐蝕等。鋁青銅以其良好的綜合力學(xué)性能和耐磨損性能越來越多被作為提高結(jié)構(gòu)材料表面性能的覆層材料,但大多是以粉末的形式通過電弧噴涂、等離子噴涂的方式制備涂層,涂層存在結(jié)合強(qiáng)度不高,孔隙率大等問題。為了改善這種情況,探索更多覆層制備方法,本課題嘗試在Q345鋼表面激光熔覆鋁青銅絲及鋁青銅片,綜合運(yùn)用正交試驗(yàn)法和單因素法研究了激光功率、掃描速度以及電流對(duì)鋁青銅絲熔覆層宏觀形貌及微觀組織的影響以及激光功率和掃描速度對(duì)鋁青銅片覆層微觀組織和顯微硬度分布規(guī)律的影響。運(yùn)用光學(xué)顯微鏡、SEM、EDS、XRD、全自動(dòng)顯微硬度計(jì)等分析了兩種鋁青銅覆層微觀組織及性能,同時(shí)研究了載荷、轉(zhuǎn)速、溫度、搭接率等不同工藝參數(shù)對(duì)兩種鋁青銅覆層摩擦磨損性能的影響,主要研究成果如下:制備的兩種鋁青銅熔覆層內(nèi)部均無氣孔與裂紋等缺陷,覆層與基體呈冶金結(jié)合。在鋁青銅絲覆層形貌方面,激光功率對(duì)覆層熔深和稀釋率影響最明顯,掃描速度對(duì)覆層熔寬和熔高影響最明顯。當(dāng)搭接率較小時(shí),鋁青銅絲覆層主要由大量灰色α相、呈樹枝狀或點(diǎn)狀的黑色κ相以及少量白色γ2相組成;搭接率較大時(shí),覆層主要由大量層片狀相間分布的灰色α相、白色γ2相以及少量點(diǎn)狀κ相組成。隨著搭接率的提高,鋁青銅絲覆層硬度先下降再升高,硬度波動(dòng)幅度逐漸下降,覆層內(nèi)部微觀組織大小以及元素分布逐漸變得均勻,搭接率60%時(shí)覆層平均硬度為225HV。與鋁青銅絲覆層不同,激光功率密度較小時(shí),鋁青銅片覆層主要由β'相與κ相組成;功率密度較大時(shí),覆層主要由γ2相與κ相組成。隨著激光功率密度的增加,鋁青銅片覆層硬度逐漸降低,且掃描速度對(duì)覆層及熱影響區(qū)的硬度影響更加顯著。鋁青銅片覆層硬度明顯高于鋁青銅絲覆層硬度,平均硬度達(dá)386HV,且硬度波動(dòng)幅度較大。對(duì)兩種鋁青銅覆層進(jìn)行摩擦磨損性能測(cè)試,發(fā)現(xiàn)隨著載荷的增大,兩種鋁青銅覆層平均摩擦系數(shù)逐漸下降,磨痕寬度、磨損量、磨痕線粗糙度逐漸增加。轉(zhuǎn)速對(duì)鋁青銅覆層平均摩擦系數(shù)影響較小,但磨痕寬度、磨損量、磨痕線粗糙度會(huì)隨著轉(zhuǎn)速的增加而增加,且轉(zhuǎn)速越高,磨痕表面越容易被氧化,黏著磨損和氧化磨損越嚴(yán)重。隨著溫度的升高,鋁青銅絲覆層平均摩擦系數(shù)、磨損量、磨痕線粗糙度先增加后減小,磨痕寬度逐漸增加;鋁青銅片覆層磨痕寬度和平均摩擦系數(shù)逐漸增加,磨損量和磨痕線粗糙度卻先下降后逐漸增加。同時(shí),兩種鋁青銅覆層磨痕氧化程度逐漸增加,黏著磨損和氧化磨損越趨嚴(yán)重,磨粒磨損逐漸減輕。
[Abstract]:With the rapid development of industry, structural parts made of carbon steel, stainless steel, alloy steel and so on are more and more widely used, and the environment is becoming more and more complex, which usually requires better surface properties of materials. Such as wear-resistant corrosion and so on. Aluminum bronze is more and more used as coating material to improve the surface properties of structural materials because of its good comprehensive mechanical properties and wear resistance. However, most of the coatings are prepared by arc spraying and plasma spraying in the form of powder. The coating has some problems such as low bonding strength and large porosity. In order to improve this situation and explore more coating preparation methods, the laser cladding of aluminum bronze wire and aluminum bronze sheet on the surface of Q345 steel was attempted in this paper. The laser power was studied by using orthogonal test and single factor method. The effects of scanning speed and current on the macroscopic morphology and microstructure of aluminum bronze wire cladding and the influence of laser power and scanning speed on the microstructure and microhardness distribution of aluminum bronze laminates were investigated. The microstructure and properties of two kinds of aluminum bronze coatings were analyzed by means of optical microscope and SEM,EDS,XRD, automatic microhardness meter. The effects of different technological parameters such as load, rotation speed, temperature and lap ratio on the friction and wear properties of two kinds of aluminum bronze coatings were studied. The main research results are as follows: there are no defects such as porosity and crack in the two kinds of aluminum bronze cladding coatings, and the coatings are metallurgical bonded with the matrix. In the aspect of the morphology of aluminum bronze wire, laser power has the most obvious influence on the penetration and dilution rate of the coating, and the scanning speed has the most obvious effect on the width and height of the coating. When the overlap ratio is small, the coating of aluminum bronze wire is mainly composed of a large number of grey 偽 phase, black 魏 phase with dendritic or dot shape and a small amount of white 緯 2 phase, and when the overlap ratio is high, the coating mainly consists of a large number of grey 偽 phases distributed between lamellar phases. White 緯 2 phase and a small amount of dot 魏 phase. With the increase of lap ratio, the hardness of aluminum bronze wire cladding decreases first and then increases, and the fluctuation of hardness decreases gradually. The microstructure and the distribution of elements in the coating become more and more uniform. The average hardness of the coating is 225 HV when the lap ratio is 60. Different from the aluminum bronze wire coating, when the laser power density is small, the aluminum bronze sheet coating is mainly composed of 尾 'phase and 魏 phase, and when the power density is high, the coating is mainly composed of 緯 2 phase and 魏 phase. With the increase of laser power density, the hardness of the aluminum bronze coating decreases gradually, and the scanning speed has a more significant effect on the hardness of the coating and the heat-affected zone. The hardness of aluminum bronze sheet coating is obviously higher than that of aluminum bronze wire coating, the average hardness is 386HVand the hardness fluctuates greatly. The friction and wear properties of two kinds of aluminum bronze coatings are tested. It is found that the average friction coefficient of the two kinds of aluminum bronze coatings decreases gradually with the increase of load, and the wear scar width, wear amount and wear line roughness increase gradually. The rotational speed has little effect on the average friction coefficient of the aluminum bronze coating, but the wear scar width, wear amount and wear line roughness will increase with the increase of rotational speed, and the higher the rotational speed, the easier the surface of the wear mark is oxidized, and the more serious the adhesion and oxidation wear is. With the increase of temperature, the average friction coefficient, wear amount and wear line roughness of aluminum bronze wire coating increase first and then decrease, and the wear mark width increases gradually, while the wear mark width and average friction coefficient increase gradually with the increase of temperature. The amount of wear and the roughness of wear line decrease first and then increase gradually. At the same time, the oxidation degree of wear marks of the two kinds of aluminum bronze cladding increases gradually, the adhesion wear and oxidation wear become more serious, and the abrasive wear decreases gradually.
【學(xué)位授予單位】：江蘇科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG174.44

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