不锈钢真空钎焊

简述了不锈钢真空钎焊技术的应用、原理、工艺及设备情况,并概述了不锈钢真空钎焊技术的发展趋势.     

铜-铝合金CPU散热器钎焊技术研究

介绍了一种环保型钎焊膏及其在CPU散热器铝合金／铜钎焊中的应用．结合散热器的铝合金-铜结构,分析了利用钎焊膏进行钎焊的过程．结果表明,钎焊可以在气体保护炉中进行,也可利用高频电源在空气气氛中进行．钎焊时在铝散热器与铜板之间发生了明显的反应,反应的液相在深度方向上有明显的晶界优先扩展取向,当在接触点发生反应产生液相后,反应得以持续进行的驱动力是Al、Cu原子通过固／液界面向反应液相中的扩散和溶解,在母材表面以下的金属学组织为Al—Cu—X和纯Al的两相组织．LHG—S2钎焊膏钎焊铜-铝合金散热器,钎焊缝的致密性完全可以达到散热器设计的技术要求,诸如传热效率及外观等．     

Development of a copper-based filler alloy for brazing stainless steels

The filler alloy of nominal composition Cu–40Mn–10Ni (all in wt%) was prepared in the form of ribbon of 40 μm thick by melt spinning technique. The ribbon exhibits narrow melting zone and comprise single phase of Cu–Mn–Ni solid solution. The melt spun ribbon successfully brazed 304 stainless steel butt joints. The formation of solid solution in the joining area without any intermetallics is observed. The bonding strength of filler alloy is achieved around 456 MPa.     

A new cooling method for vacuum brazing of a stainless steel plate–fin structure

This paper presents a new cooling method for vacuum brazing of 304 stainless steel plate–fin structures with Nickel-based BNi2 filler metal. The tensile tests and scanning electron microscope (SEM) observations have been performed. Quick cooling method and a new developed slow cooling method have been used, respectively, to discuss the influence of cooling methods on tensile strength and microstructures. The quick cooling is performed by dry nitrogen and wind cooling system directly from brazing temperature 1050 °C. The new slow cooling method is self-cooling in vacuum furnace from 1050 to 620 °C, then it is changed to quick cooling with dry nitrogen and wind cooling. The results show that quick cooling method should not be used because thermal cracks will be created and decrease the strength. The new developed slow cooling method can greatly improve the brazing performance.     

提高钎缝耐热性的新途径

高温合金构件真空钎焊通常采用Ni-Cr-Si-B系钎料 ,在钎缝中会形成连续分布的共晶组织 ,使钎缝重熔温度降低 ,耐热性变差 .为解决这一难题 ,研究了一种粉末冶金 -钎焊工艺 ,结果表明 :该工艺可以消除钎缝中低熔点共晶组织 ,并能实现钎缝固溶强化和第二相强化 ,从而提高了钎缝的耐热性 .用K40 3和GH40 3 7合金钎焊接头持久性能分别达到母材的 75 %和 95 %的水平 ,该工艺已用于涡轮导向叶片的修补 .     

A study of the reactive brazing of a silicon nitride to steel using ternary Ag-Cu-Ti: microstructure and mechanical strength of the bonds

A study of the behaviour of Ag-Cu-Ti braze in contact with a ceramic - its wetta bility, evolution and reactivity-by different means of investigation gives some insight into the mechanisms involved in reactive brazing. Joints between siliconnitride and a structural steel were made by brazing under various conditions of temperature, hold time and a tmosphere. The room temperature mechanical strength measured in a shear test may be correlated to some microstructural and physicochemical features. The heterogeneous microstructure observed for almost all Ag-Cu-Ti brazes is explained by immiscibility in the liquid state with an equilibrium established between Ag-Cu-rich and Cu-Ti-rich liquids. It is shown that high temperatures (> 910°C) ensure a more efficient reaction of the titanium-rich phases and so a good wetting of the siliconnitride. Consequently, the shear strengths of bonds between siliconnit ride and steel achieved by using a sufficiently high brazing temperature are optimal (123-158 MPa).     

Effect of brazing temperature on tensile strength and microstructure for a stainless steel plate-fin structure

This paper presented a vacuum brazing technology for 304 stainless steel plate-fin structures with BNi2 filler metal. The effect of brazing temperature on tensile strength and microstructure has been investigated. The tensile strength is increased along with the increasing of brazing temperature. The microstructure is very complex and some Boride compounds are generated in the brazed joint. Full solid solution can be generated in the middle zone of joint when the brazing temperature is increased to 1100 °C. The brittle phases always exist in the fillet no matter how the brazing temperature changes, but the microstructure in fillet becomes more uniform and the tensile strength is increased with the brazing temperature increasing. In total, the brittle Boride compounds are decreased with the brazing temperature increase. Brazing with a filler metal thickness 105 μm and 25 min holding time, 1100 °C is the best suitable brazing temperature and a tensile strength of 82.1 MPa has been achieved for 304 stainless steel plate-fin structure.     

Microstructure of Ni-NiCr laminated composite and Cr18-Ni8 steel joint by vacuum brazing

Vacuum brazing of Ni-NiCr laminated composite to Cr18-Ni8 steel was carried out using Ni-Cr-Si-B amorphous foil. Microstructure characteristic of the brazed joints was investigated by scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), field-emission scanning electron microscope (FE-SEM) and microsclerometer. Ni-Cr-Si-B amorphous foil exhibited good wettability on Ni-NiCr laminated composite. The brazed region consisted of γ-Ni solid solution and Ni-B eutectic. An excellent bonding with shear of 170 MPa was obtained. An interface of Ni₃B precipitated in Ni cover layer near the brazed region. Microhardness of the interface was 500 HV. There was an interface consisting of fine boride granules in Cr18-Ni8 steel close to the brazed region and microhardness of the interface was 250 HV. Bonding behavior of the brazed joint was described according to the microstructure characteristic.     

Zr-Cu-Ni非晶钎料真空钎焊TiAl合金/316L不锈钢接头的界面组织与剪切性能

采用自主设计制备的Zr-42.9Cu-21.4Ni非晶钎料对TiAl合金和316L不锈钢进行真空钎焊,研究钎焊温度和钎焊时间对TiAl合金/316L不锈钢异种金属接头微观组织和剪切性能的影响。结果表明：钎缝界面可以划分为6个不同的反应层。1040 ℃/10 min下制备的钎焊接头从TiAl合金到316L不锈钢侧界面组织依次为γ(TiAl)+AlCuTi/α₂(Ti₃Al)+AlCuTi/AlCu+ZrCuNi+FeZr/Cu₈Zr₃+ZrCuNi+TiFe+Fe₂Zr/FeZr+Fe₂Zr+TiFe₂+ZrCu/α-(Fe, Cr)。随着钎焊温度的升高,接头的抗剪强度先升高后降低。当钎焊温度为1040 ℃和钎焊时间25 min时,接头抗剪强度达到最大值162 MPa。断口分析表明,接头在FeZr+Fe₂Zr+TiFe₂+ZrCu界面处萌生,沿着Cu₈Zr₃+ZrCuNi+TiFe+Fe₂Zr和α-(Fe, Cr)扩展,呈解理断裂。     

喷丸预处理对铝合金与钢TIG熔-钎焊的影响

为了使铝合金与钢的连接更加牢固,以Al-Si(6%~8%)为钎料,采用TIG熔-钎焊对5052铝合金和镀锌钢板进行连接,并对铝合金板的熔-焊区进行表面喷丸预处理,研究了表面喷丸对接头界面组织及力学性能的影响.研究表明:喷丸预处理能细化接头熔焊区柱状晶晶粒并使其分布更均匀,促进钢/熔池金属间的界面反应;表面喷丸明显改变了钢/铝扩散层厚度,厚度由6.0μm增加到9.5μm.力学性能测试结果表明,表面喷丸显著改善了连接质量,接头拉剪强度达到238.6 N/mm.