电弧喷涂层温度场数值模拟

详细介绍了电弧喷涂层沉积过程中三维温度场有限元模拟技术 ,采用有限元分析软件计算了不同工艺、不同时刻以及不同位置涂层内的温度场 ,在建立传热模型过程中考虑了金属液滴束向涂层的传热与传质以及涂层向系统外的热量散失。采用在厚度方向以微小层叠加来模拟涂层的增厚 ,以此为基础构造涂层有限元计算几何模型 ,逐层激活层单元参与计算过程 ,实现移动边界以充分模拟真实的喷涂沉积过程。以实验验证计算结果 ,并详细讨论了喷涂沉积速率、界面传热系数以及间歇喷涂对涂层温度场的影响     

提高电弧喷涂层与基体结合强度的新工艺

介绍一种新型电弧喷涂技术--粉末复合电弧喷涂技术。运用粉末复合电弧喷涂技术对轴类零件和轴承座内孔进行喷涂。在喷涂前,对轴类零件粗车螺纹并进行挤压,使基体表面形成钩子形状,增加喷涂层和基体的机械结合力;对轴承座内孔进行堆焊,将大表面分割成小表面,减少了喷涂层收缩时形成的裂纹,提高了喷涂层与基体的结合强度。这两种方法适合大型轴类零件的表面强化和修复。     

表面处理方法对电弧喷涂涂层强度影响的试验研究

电弧喷涂表面粗糙处理效果直接影响到喷涂质量,而目前实际生产中不同的表面粗糙处理方法都有应用。为此采用活塞拉拔式试验方法,评价了喷砂、镍丝电弧拉毛、Ｎｉ／Ａｌ底层喷涂及砂轮磨削四种表面粗糙处理方法。试验结果显示：喷砂法是电弧喷涂较理想的表面粗糙处理方法,Ｎｉ／Ａｌ底层喷涂可获得较高的涂层结合强度,但其成本较高,可用于不宜喷砂的工件;镍丝电弧拉毛法和砂轮磨削法涂层结合强度低,不宜在生产中应用。     

电弧及高速电弧喷涂FeCrAl涂层的微观性能研究

用相同的喷砂和喷涂工艺参数,分别在４５＾＃钢基体上制备了电弧喷涂与高速电弧喷涂ＦｅＣｒＡｌ涂层,用扫描电镜分析了它们的表面形貌,测试分析了两种涂层及各种基体在距涂层－基体界面不同距离上的显微硬度值,得到了电弧喷涂及高速电弧喷涂基体上的热影响区宽度,讨论了涂层的显微组织对其硬度的影响,并测试分析了涂层和基体的截面线波动系数。试验结果表明,高速电弧喷涂ＦｅＣｒＡｌ涂层比普通电弧喷涂ＦｅＣｒＡｌ涂人有更     

电弧喷涂制模技术的研究及应用

将电弧喷涂技术成功地运用到模具制作上,开辟了电弧喷涂技术应用的一个新领域,利用电弧喷涂制作具有周期短、费用低、效益高的显著特点,尤其对一些形状复杂、有各种装饰花纹的型腔模具理 明显的经济效益和实用价值。     

电弧喷涂技术的现状与发展

介绍了电弧喷涂技术的发展历程、特点及应用，重点阐述了电弧喷涂材料及设备的研究现状与发展。指出粉芯丝材作为电弧喷涂材料新的发展方向，可以用其尝试获得非晶涂层、金属陶瓷涂层及纳米涂层。电源和喷枪是电弧喷涂设备的关键部件，逆变技术的应用是电弧喷涂电源的发展方向，而喷枪则向着高速、高效和稳定送丝的方向发展。     

高速电弧喷涂电流波动对涂层性能的影响

电弧喷涂时的电压和电流是对喷涂层性能有重要影响的两个电参数。由于喷涂过程中电压的波动范围不大 ,而电流的波动范围较大 ,因此喷涂电流的波动对电弧喷涂过程的稳定性及涂层质量的影响更为突出。在保持其它参数 (如雾化气体压力、喷涂距离、喷枪角度等 )不变的前提下 ,研究了高速电弧喷涂时的电流波动率对涂层的孔隙率、显微硬度、耐磨性等方面的影响 ,当电流波动幅度减小时 ,涂层的综合性能将会得到提高。文中从理论上对电流波动影响涂层性能的机理进行了分析 ,认为电流波动造成电弧喷涂雾化粒子尺寸、温度、空间分布等不均是造成涂层综合性能不高的主要原因。     

电弧喷涂层高温氧化行为

对3种电弧喷涂涂层进行了800℃高温氧化腐蚀试验，比较了不同含铬丝材电弧喷涂层的高温氧化行为，分析了涂层中铬的作用及其抗腐蚀机理，结果表明，含铬量对涂层的抗氧化性能有明显影响，含铬量越高，形成的保护性氧化铬膜越致密，相同时间形成的氧化膜越薄，腐蚀质量增值越低，由于粉芯丝材在喷涂过程中铬烧损较多，铬在涂层中的分布不均匀，形成的保护膜较疏松，使涂层抗蚀性降低。     

电弧喷涂线材的研究进展及应用

在简述电弧喷涂基本原理的基础上,分类介绍了各种电弧喷涂线材性能特点、发展现状和主要应用,指出了各电弧喷涂线材的发展方向.     

钢基模具喷涂层温度场和应力场模拟分析

采用有限元分析软件计算不同时刻以及不同位置涂层内的温度场、应力场,分析电弧喷涂方法制造模具时的沉积过程.在建立传热模型过程中,采用在厚度方向以微小层逐层叠加来模拟涂层的增厚,并应用生死单元法逐层激活层单元参与计算过程,以模拟真实的喷涂沉积过程,获得了喷涂层内温度场、应力场的分布情况.并在此计算的基础上,分析了应力的分布对涂层失稳以及残余应力分布的影响,为模具尺寸设计和喷涂工艺制订提供了依据.     

电弧喷涂涂层的红外热成像检测

通过分析主动式红外热成像方法的检测原理,结合国外检测案例,确定了红外热成像方法对涂层质量检测的适用性.针对电弧喷涂涂层与基体分层缺陷,开展了涂层质量的红外热成像检测试验.结果表明,主动式红外热成像方法能够实现对涂层内部分层缺陷的准确、快速和非接触检测,利用热扩散曲线能够对分层程度进行有效区分.     

电弧喷涂铝基涂层耐高温硫化腐蚀性能的研究

对电弧喷涂铝基涂层在600 ℃条件下的耐硫化氢腐蚀性能进行了研究,并与Fe-Al涂层和A304不锈钢的耐H2S腐蚀性能进行了对比.结果表明,铝基涂层的耐硫化氢腐蚀性能优于Fe-Al涂层和A304不锈钢.铝基涂层具有良好的耐H2S腐蚀性能的主要原因是涂层中的Al含量很高,在腐蚀过程中能优先生成A1的腐蚀产物以及涂层中含有多种铝的金属间化合物,能够阻碍硫原子向金属内部渗人,从而保证了铝基涂层具有良好的耐硫化腐蚀性能.     

自动化电弧喷涂路径对涂层残余应力的影响

喷涂路径是影响电弧喷涂层残余应力的重要因素之一.利用自行开发的自动化电弧喷涂系统设计了四种典型的喷涂路径,采用X射线残余应力测试仪测量了不同路径下制备的82B高碳钢涂层的表面残余应力分布,并利用金相显微镜和X射线衍射仪分析了涂层的组织形貌与相组成.试验显示,环形喷涂路径制备的涂层的残余应力分布最均匀,最大应力值最低;平行对称路径的情况最差.组织分析表明涂层主要由氧化物和块状马氏体组织组成.最后探讨了高碳钢涂层骤冷应力、热应力和相变应力三种因素的影响机理.     

Effect of arc distance on temperature field and weld shape during double-sided arc welding

A new high efficiency welding method, double-sided double arc welding with double powers (DSAW-D), is developed for thick plate of low alloy high strength steel in this study. It is well known that the thermal cycles have an important influence on the microstructure, shape, stress, distortion and mechanical property. The DSA W-D method can control the tempernture field on a wide range by regulating the distance between two arcs, improve the rnicrostructure and prevent hot and cold cracking of high strength steel. But at present, the effect of arc distance on the temperature field and shape is not clear. Therefore, the paper researches the effect of arc distance on the temperature field and weld pool during DSA W-D using finite element method. The transient temperature field of different arc distance in DSAW-D is calculated.To verify the numerical results, the temperature is measured by the thermo-couple and the calculated results agree approximately with experimental data. Farther, the thermal property and mutual effect of double-sided arcs are investigated. The temperature distributions and weld pool profile at different arc distances are obtained. The results show that arc distance is a very important factor to affect the heat process.     

基于电弧喷涂技术的钢基模具快速制造方法

在由快速原形技术得到的3D模型上采用热喷涂方法进行逐层喷涂,最终沉积为具有预定内部型腔尺寸和外观形状的钢基汽车拉延模具.这些模具采用高强钢丝材喷涂而成,能够满足模具使用寿命的要求.通过喷涂丝材选择和喷涂层冷速的控制来保证在沉积层中形成马氏体组织,使沉积层具有足够的硬度和耐磨性,并具有良好的抗裂性.还通过有限元方法分析了沉积层的温度和应力,以保证模具的尺寸精度.采用这种工艺制作了实际生产应用的钢基拉延模具,其尺寸精度和力学性能可以满足要求,并已经在生产中试用.     

高速电弧喷涂Fe-Al金属间化合物涂层

采用粉芯丝材和高速电弧喷涂技术(HVAS)制备了Fe-Al金属间化合物涂层,并研究了涂层的显微组织和室温至650℃的滑动摩擦磨损性能.结果表明:Fe-Al涂层的平均成分为Fe-20.0Al-14.1O(摩尔分数,%),主要相是Fe3Al,FeAl,α-Fe,Al2O3及少量Al;涂层具有较高的结合强度和硬度、较低的孔隙率及较高的高温耐磨性;高温下磨损面形成了大面积的氧化物保护层,降低了涂层的摩擦因数,而剥层磨损是涂层的主要磨损机制.涂层中Fe3Al和FeAl金属间化合物相较高的高温强度和硬度能有效地阻碍裂纹的产生、扩展及扁平颗粒的断裂,从而使Fe-Al涂层表现出优异的高温耐磨性.     

Configuration optimization of high velocity arc spraying gun

In order to improve the in-flight characteristics of the atomizing droplets during high velocity wire arc spraying (HVAS), some changes have been operated on the original design of the HVAS gun configuration. A comparative study was carried out to investigate the microstructure and properties of the coatings produced by the original design spraying gun and the modified one, using 3Cr13 wires of 3 mm in diameter. The characteristics of their jets were examined during spraying. The results indicate that, the included angle between the two wires and the distance from the nozzle to the meeting point of the two vires may have a strong influence on the characteristics of the in-flight droplets and then the coatings. The jet divergence is found to be lower than that of the original one (about 12° against 25°). By modified gun, the adhesion strength, the microhardness and porosity of the coating deposited by modified gun are increased by 39% and 9% respectively. And the porosity of the coatings is decreased by 57%.     

Effect of substrate temperature on adhesion strength of plasma-sprayed nickel coatings

We plasma-sprayed nickel coatings on stainless steel and cobalt alloy coupons heated to temperatures ranging from room temperature to 650 °C. Temperatures, velocities, and sizes of spray particles were recorded while in-flight and held constant during experiments. We measured coating adhesion strength and porosity, photographed coating microstructure, and determined thickness and composition of surface oxide layers on heated substrates. Coating adhesion strength on stainless steel coupons increased from 10–74 MPa when substrate temperatures were raised from 25–650 °C. Coating porosity was lower on high-temperature surfaces. Surface oxide layers grew thicker when substrates were heated, but oxidation alone could not account for the increase in coating adhesion strength. When a coupon was heated to 650 °C and allowed to cool before plasma-spraying, its coating adhesion strength was much less than that of a coating deposited on a surface maintained at 650 °C. Cobalt alloy coupons, which oxidize much less than stainless steel when heated, also showed improved coating adhesion when heated. Heating the substrate removes surface moisture and other volatile contaminants, delays solidification of droplets so that they can better penetrate surface cavities, and promotes diffusion between the coating and substrate. All of these mechanisms enhance coating adhesion.