Wetting behaviour of Cu based active brazing alloys on siliconised graphite

Abstract

The effects of Al and silicon additions to Cu based brazing alloy and the surface free silicon on siliconised graphite substrate on the wetting behaviour of the siliconised graphite by Cu–Al–Si–Ti alloys were investigated using the sessile drop technique at 1100°C. The contact angles were measured and the interfacial reactions were analysed. It was shown that surface free Si on siliconised graphite had a great positive effect on the contact angle. Furthermore, interfacial reactions could be controlled by adjusting the contents of Si and Al in brazing alloys.     

Development of Ag based brazing filler metal with low melting point

Abstract

This study was carried out to develop cadmium free silver based brazing filler metals that meet the following requirements. First, they have to have a melting point lower than that of BAg-1 brazing filler metal. Second, they have to have not only good wetting characteristics and the ability to produce a sound joint with excellent mechanical properties but also plastic formability. Using the calculated phase diagrams on Ag–Cu–Zn–Sn quaternary system alloys, the authors selected several alloys with a possibility of meeting the above requirements. The melting point and other properties, such as hardness and brazeability of the selected alloys, were evaluated. As a result, the authors successfully developed silver based brazing filler metals that have a low melting point below ～600°C and meet the above requirements by adding a small amount of indium as an alloying element into the Ag–Cu–Zn–Sn quaternary system alloy. The newly developed brazing filler metals are slightly inferior in wetting characteristics to BAg-1; however, the brazing filler metal containing ～3 mass-% indium element showed wetting characteristics comparable to those of BAg-1. Furthermore, the new brazing filler metals could produce joints with a high tensile strength equivalent to ～83% of that of a joint brazed using BAg-1.     

Investigation on wetting behaviour of B4C by Ni based brazing alloys

Abstract

In the present study, the wetting behaviour of boron carbide by Ni based brazing alloys has been investigated. Based on the results of wetting experiments using sessile drop method, it has been revealed that these filler metals are generally able to wet B₄C surface. This relates to the reactivity of Ni with this ceramic material. The presence of Si in these fillers and its reactivity with the surface of B₄C play a major role in wetting improvement. In addition, the existence of Cr in the filler also improves this behaviour. Based on the results of wetting tests, a low wetting angle of 26° was obtained for the filler metal having the highest amounts of Si and Cr. In this article, the microstructure and chemical composition of the interfacial phases have been studied.     

锡镀层对BAg50CuZn钎料性能的影响

以BAg50CuZn钎料为研究对象,在其表面电镀锡,借助扫描电镜(SEM)观察锡镀层的表面形貌,采用差热分析仪(differential scanning calorimetry,DSC)和润湿试验炉分析锡镀层对合金钎料熔化温度和润湿性能的影响,并对镀覆锡后合金钎料的成分进行了讨论.结果表明,随着钎料表面镀覆Sn元素含量增加,合金钎料的DSC吸热峰向左偏移、熔化温度降低,钎料的润湿铺展性能呈上升趋势.在镀覆Sn元素含量为4.8%(质量分数)时,合金钎料表面锡镀层平整、致密,钎料的铺展面积最大,为236 mm2.镀覆元素Sn后的钎料中,Ag,Cu,Zn元素含量均减少,元素含量降低幅度大小顺序依次为Cu,Ag,Zn.     

Laser brazing of alloy 600 with precious filler metals

Abstract

The diode laser brazing of Ni base heat resistant alloy with precious filler metals has been conducted using the tandem beam for preheating and brazing. A couple of 1 mm thick plates of alloy 600 (Inconel 600) were butt brazed using Au–18Ni, Ag–10Pd and Ag–21Cu–25Pd filler metals of 0·5 mm diameter with a brazing flux. Sound butt joints which were free from brazing defects such as porosity and lack of penetration could be obtained at brazing clearances of 0·1–1·5 mm. The tensile strength of the braze joint produced using Ag–Pd filler metal increased with decreasing brazing clearance and reached ～70% of the base metal strength at a brazing clearance of 0·1 mm while those obtained by using Au–Ni and Ag–Cu–Pd filler metals were comparable with the base metal strength at any clearances between 0·1 and 1·5 mm. The laser brazing technique could be successfully applied to the brazing of Ni base superalloy to attain a joint with high performance and reliability.     

Pulsed gas metal arc welding of Al–Cu–Li alloy

Abstract

An experimental Al–Cu–Li–Mg–Ag–Zr type alloy in the form of 13.7 mm thick plates was studied for its fusion characteristics using gas metal arc welding (GMAW) and pulsed gas metal arc welding (P-GMAW). High copper 2319 filler of 1.6 mm diameter was used. The burn-off characteristics of 2319 filler wire in GMAW and P-GMAW were experimentally determined, including the relation between pulse current and pulse duration for the desired one-drop detachment per pulse (ODPP) condition and feasible range of pulse parameters. The effect of welding parameters on bead geometry and shape relationships was investigated through beadon-plate experiments in the welding current range above the spray transition current. Reasonably good weld beads were obtained in P-GMAW at currents as low as 194 A and welding speeds of 45 cm min^–1. P-GMAW yielded significantly higher weld penetration compared to GMAW.     

基于低银钎料的金刚石薄壁钻钎焊工艺研究

根据Ag、Cu、Zn、Cd、Ni、Co、Mn等元素在钎料中的作用和特点,通过分析和选择,研发了一种新型钎料,并对其熔点、强度以及钎焊工艺进行了研究.结果表明:新开发的低银钎料ZB-1中的表面活性元素能显著降低液态钎料的表面张力,细化合金晶粒,延缓钎焊过程中钎料的氧化,在改善钎料润湿性的同时净化钎缝晶界,从而提高钎缝的抗...     

Brazing method to join a novel Cu54Ni6Zr22Ti18 bulk metallic glass to carbon steel

This study joined a novel Cu-based bulk metallic glass (BMG) to carbon steel using a brazing process. Cu₅₄Ni₆Zr₂₂Ti₁₈ BMG was brazed to SS400 carbon steel using filler metal at 713?K under a compressive stress of 15?MPa for 3?min. Considering the relatively low glass-forming ability, pure Zn and Zn–Ag–Al filler metals were selected to suppress the crystallisation during a reheating thermal cycle. A sound bonding interface without notable chemical diffusion was obtained using the suggested brazing method, particularly with the Zn–Ag–Al filler. This gave rise to considerable improvement in shear bonding strength, from 9 to 45?MPa, when replacing the Zn filler with the Zn–Ag–Al filler. The present method also induced no marked change in phase composition of the BMG due to the low bonding temperature and short bonding time. Slight variations in glass transition temperature and crystallisation temperature would result from a thermal annealing effect.     

Effects of flow of liquid filler metal and base metal composition on erosion characteristics during aluminium brazing

When automotive heat exchangers such as radiators and condensers are manufactured, serious erosion caused by the molten filler metal from the header occasionally occurs on the tubes during brazing. In our previous study, we proposed a novel experimental method which consisted of using a feeder and a base plate on a gutter made for the flow of molten filler, and we quantitatively evaluated the relationship between the volume of flowing molten filler and the level of erosion.

We used Al–12%Si molten filler to investigate the effect of chemical composition, in particular, the Si content of the base plane, on the level of erosion. When Al–0–1.2%Si alloys that have a solidus temperature that is higher that their brazing temperature were used, the level was almost constant irrespective of the Si content of the base metal. However, when Al–0–2.0%Si alloys that have a solidus temperature that is lower than their brazing one are used, the level increases.     

SiC陶瓷与TiAI合金的真空钎焊

采用Ag-Cu-Ti钎料对常压烧结的SiC陶瓷与TiAl金属间化合物进行了真空钎焊,并对接头的微观组织和室温强度进行了研究。结果表明,利用Ag-Cu-Ti钎料可以实现SiC与TiAl的连接;接头界面具有明显的层状结构,即由Ti-Cu-Si合金层、富Cu相与富Ag相的双相层和Ti-Al-Cu合金层组成;在1173K和10min的钎焊条件下,接头室温剪切强度达到173MPa。     

SnAg1.0Cu0.5对Ag30CuZnSn药芯钎料润湿性能及钎焊接头力学性能的影响

向Ag30CuZnSn药芯钎料药粉中添加SnAg1.0Cu0.5(SAC105)粉末,研究了不同SAC105含量对Ag30CuZnSn药芯钎料钎缝组织及钎焊接头性能的影响.结果表明,SAC105的加入可以显著提高Ag30CuZnSn药芯银钎料的润湿铺展性能,随着SAC105的添加量增加,Ag30CuZnSn药芯银钎料的...     

Evolution of microstructure and phase composition of joints with ultrasonic-assisted resistance brazing

ABSTRACT

Zn–2Al alloy is used as a filler metal for brazing of aluminium 6063 alloys by ultrasonic-assisted resistance brazing (RB) technology. The evolution of the microstructure and phase composition under the effects of the electric field and ultrasonic vibration were studied. The results show that ultrasonic cavitation can remove the existing oxide films effectively and inhibit element segregation, which help obtain joints with good metallurgical bonding. In comparison to RB joints, which exhibit a coarse dendritic structure, a uniform dendritic structure was obtained in the ultrasonic-assisted resistance joints. Furthermore, the combined electric and ultrasonic field has a significant effect on grain size and on dissolution during brazing. With the application of ultrasonic vibration, the diffusion between the base metal and the Zn–2Al filler metal intensifies.     

热解还原法制备镀镍ZrO2增强低银SnAgCu系复合钎料及其钎焊

本文采用热分解-还原法制备镀镍ZrO2增强相,粉末冶金法制备镀镍ZrO2增强Sn1.0Ag0.5Cu复合钎料,研究了ZrO2纳米颗粒表面金属化以及其对Sn1.0Ag0.5Cu复合钎料的微观结构、材料性能及钎焊接头的影响。结果表明:经机械预处理的ZrO2粒径减小、团聚降低;采用热分解-还原法成功地制备出了镀镍ZrO2增强相,Ni粒子以8-11 nm间距均匀附着于ZrO2表面,ZrO2(02)和Ni(11)界面呈半共格关系;添加适量镀镍ZrO2对Ni/ZrO2-Sn1.0Ag0.5Cu复合材料的熔点、电阻率影响不大,提高了润湿性和抗拉强度,在镀镍ZrO2增强相添加量为0.7 wt.%时Ni/ZrO2-Sn1.0Ag0.5Cu复合钎料抗拉强度、钎焊接头剪切强度均达峰值,较基体材料的相比提高了43.3%、40%。随着Ni-ZrO2增强相的添加,复合钎料钎焊接头的断裂位置由界面IMC层向过渡区的近钎缝侧移动,断裂机制由韧-脆混合断裂逐渐转为韧窝为主的韧性断裂。     

Zn-Al钎料钎焊Cu/Al接头组织和性能(英文)

使用不同成分的Zn-Al钎料对铜铝异种金属进行火焰钎焊,研究其力学性能。利用光学显微镜、扫描电镜和能谱研究不同Zn-Al钎料对Cu/Al钎焊接头钎焊性、力学性能及显微组织的影响。结果表明:随着Al含量的增加,Zn-Al钎料在Cu和Al上的铺展面积逐渐增大。当钎料中Al含量为15%时,Cu/Al接头的抗剪强度达到最大值88MPa;随着组织的变化,钎缝硬度值呈现HV122到HV515不等的分布。另外,钎缝组织的成分主要为富Zn相和富Al相,但是当钎料中Al含量为2%和15%以上时,靠近Cu侧的界面处会分别形成CuZn3和Al2Cu两种完全不同的金属间化合物。研究Zn-Al钎料中铝含量对Cu/Al接头界面化合物类型的影响。     

Microstructure and Property of Cu/Al Joint Brazed with Al-Si-Ge Filler MetalEI北大核心CSCD

Cu/Al brazing has good prospect for applications in the air conditioning and refrigeration industry. A suitable filler metal is the key of Cu/Al brazing. The chemical and physical properties of the filler metal have great influence on the brazing process and parameters. And the strength of the brazing joint is closely related to the properties of the filler metal and the brazing process. While the previous studies have not developed a kind of Cu/Al brazing filler metal which can achieve a tough joint at a low brazing temperature. In this work, the Al-5.6Si-25.2Ge filler metal was first used to braze Cu/Al dissimilar metals, and the melting characteristics of the filler metal, spreading wettability, Cu interfacial structure and strength of brazed joint were investigated systematically. Additionally, the common Zn-22Al filler metal was also used for comparison. The results show that the Al-5.6Si-25.2Ge filler metal possesses low melting temperature (about 541 degrees C) and excellent spreading wettability on Cu and Al base metals. The interfacial structure of Al-5.6Si-25.2Ge/Cu was CuAl2/CuAl/Cu3Al2. The thickness of planar CuAl and Cu3Al2 phases was only 1 similar to 2 mu m, and the thickness of cellular CuAl2 phase was about 3 mu m. The interfacial structure of Zn-22Al/Cu was CuAl2/CuAl/Cu9Al4, but the average thickness of the CuAl2 layer was up to 15 mm. The test results of the shearing strength show that the shearing strength of the Cu/Al joint brazed with Zn-22Al filler metal was only 42.7 MPa, but the shearing strength brazed with Al-5.6Si-25.2Ge filler metal was higher (53.4 MPa).     

Analysis of intermetallic layer in dissimilar TIG welding–brazing butt joint of aluminium alloy to stainless steel

Abstract

Intermetallic layer of dissimilar tungsten inert gas welding–brazing butt joint of aluminium alloy/ stainless steel has been studied. A visible unequal thickness intermetallic layer has formed in welded seam/steel interface, and the thickness of the whole layer is <10 μm. The interface with Al–12Si filler metal consists of τ ₅-Al₈Fe₂Si layer in welded seam side and θ-(Al,Si)₁₃Fe₄ layer in steel side with the hardness values of 1025 and 835 HV respectively, while the interface with Al–6Cu filler metal consists of θ-Al₁₃(Fe,Cu)₄ layer with the hardness of 645 HV. The average tensile strength of the joint with Al–12Si filler metal is 100–120 MPa, and the fracture occurs at θ-(Al,Si)₁₃Fe₄ layer, while the joint with Al–6%Cu filler metal presents high crack resistance with tensile strength of 155–175 MPa, which reaches more than 50% of aluminium base metal strength.     

Brazing of A5056 aluminium alloy with the aid of ultrasonic vibration using Ag filler metal

In order to produce a high strength brazed joint of A5056 aluminium alloy containing magnesium of about 5 mass%, the authors applied a flux-free brazing method with the aid of ultrasonic vibration to the aluminium alloy by selecting pure Ag foil as brazing filler metal and examined the effect of brazing conditions on the joint properties. The main results obtained in this study are as follows.

At a brazing temperature of 570°C, just above the eutectic point of Al–Ag binary system, application of ultrasonic vibration for 4.0 s provided the brazed joint with the maximum tensile strength and the strength decreased with the application time. When the brazing temperature was varied from 550 to 580°C and the application time of ultrasonic vibration was kept constant at 4.0 s, the joint brazed at 560°C attained the maximum tensile strength and fractured in the base metal. It was found that using a pure Ag foil as brazing filler metal successfully brazed A5056 aluminium alloy and the joint strength was equivalent to that of the base metal. Fracture of the joint was prone to occur along the (Al₃Mg₂ + Al solid solution) phase with high hardness formed at the grain boundary of the base metal. The amount of the hard (Al₃Mg₂ + Al solid solution) phase increased with the ultrasonic application time and the brazing temperature. It seemed that the increase of the hard (Al₃Mg₂ + Al solid solution) phase mainly caused the brazed joint strength to decrease.     

Effect of Ti content in Ag–Cu–Ti activated filler metal on dissimilar joint formation of sialon and WC–Co alloy by laser brazing

Laser brazing was carried out for dissimilar joining of sialon and a WC–Co alloy. Eutectic type Ag–Cu alloys as filler metals with different Ti content ranging from 0 to 2·8 mass-% were used to investigate the effects of Ti on the interface structure and strength of the joint. The filler metal sheet was sandwiched between a sialon block and a WC–Co alloy plate, and a laser beam was irradiated selectively on the WC–Co alloy plate. The brazed joint was obtained using the filler metal containing >0·3 mass-%Ti. TiN, Ti₅Si₃, and Cu₄Ti layers were formed at the interface of sialon and brazed metal as compound layers. The shear strength of the brazed joint increased with increasing Ti content in the filler metal in the range 0·3–1·7 mass-%, reaching a maximum value of 106 MPa. However, the strength decreased when the Ti content became higher than 1·7 mass-%.     

Partial and integral enthalpy of molten Ag–Al–Cu alloys

The partial and integral enthalpies of mixing of molten, ternary Ag–Al–Cu alloys were determined at 1146 K using a calorimeter of the Tian–Calvet type. Measurements were performed starting from pure Al to about 40 at.% Al along three sections with Ag:Cu ratios of about 1:3, 1:1 and 3:1. The values of the partial enthalpies of Cu, h_Cu≅−40 kJ mol⁻¹, are rather constant from 1>x_Al>0.6. The values of the partial enthalpies of Ag decrease from h_Ag=+5 kJ mol⁻¹ to −10 kJ mol⁻¹. The minimum values at about 40 at.% Al for the integral molar enthalpy are −18 kJ mol⁻¹ for Cu:Ag=3:1, −12.5 kJ mol⁻¹ for Cu:Ag=1:1 and −8,5 kJ mol⁻¹ for Cu:Ag=1:3; the error is ±5%. This behaviour is in agreement with the concept of Fermi enthalpy and corresponds to a transfer of one electron from aluminium to the not fully occupied bands of copper and silver, respectively. The existence of a ternary liquid non-stoichiometric compound with a very broad range of stability is claimed for alloys with about 0<x(Al)<0.5, too.     

Microstructure and strength of brazed joints of TiB2 cermet to TiAl-based alloys

In this study, TiB2 cermet and TiAl-based alloy are vacuum brazed successfully by using Ag-Cu-Ti filler metal.The microstructural analyses indicate that two reaction products, Ti ( Cu, Al ) 2 and Ag bused solid solution ( Ag ( s. s ) ) , are present in the brazing seam, and the iuterface structure of the brazed joint is TiB2/TiB2 Ag ( s. s ) /Ag ( s. s ) Ti ( Cu,Al)2/Ti( Cu, Al)2/TiAl. The experimental results show that the shear strength of the brazed TiB2/TiAl joints decreases us thebrazing time increases at a definite brazing temperature. When the joint is brazed at 1 223 K for 5 min, a joint strength up to 173 MPa is achieved.