激光钎焊金刚石磨粒界面微结构分析

采用Ni基合金钎料,在Ar气保护条件下,对金刚石磨粒进行了激光钎焊试验研究.采用扫描电镜(SEM)和能谱仪(EDS)及X射线衍射仪(XRD)对钎焊金刚石试样进行理化分析,探讨了钎料与金刚石界面处碳化物的形成机理.结果表明,激光钎焊过程中在金刚石表面附近形成的富Cr层与金刚石表面的C元素反应生成碳化物,在钢基体结合界面上Ni-Cr合金钎料和钢基体中的元素相互扩散形成化学冶金结合.     

Cr、Ti金属粉改善Ag-Cu-Zn合金对金刚石的钎焊性能研究

本文通过在Ag-Cu-Zn钎料合金与金刚石之间添加Cr、Ti金属粉,改善Ag-Cu-Zn合金对金刚石的钎焊性能,并在不同的保护条件下(真空、Ar气体、无机盐覆盖、C粉覆盖)钎焊金刚石磨粒;采用扫描电镜和光学显微镜对钎焊金刚石表面形貌以及金刚石一钎料合金-钢基体之间界面的微观结构进行了观察;结果表明添加Cr粉可以在空气中对金刚石实现良好的钎焊,添加Ti粉则需要在真空中或者覆盖C粉才能保证钎焊效果较好;在金刚石与钎料合金的界面处发现Cr和Ti元素的富集,这提高了Ag-Cu-Zn合金对金刚石的润湿性.     

High temperature brazing of diamond tools

1 INTRODUCTIONThe demand for superhard and precisionmachining and grinding tools has been increasedbecause of strict control of machining tolerancesfor advanced and superalloy componentsin additionto their application in cutting and grinding ofstones ,concrete structures or composite materials .Previous work[1 5]has reported the developmentand applications of these tools ,alloys and compos-ites which can be suitable for machining,joining ofdissi milar materials ,and in other fields . Diamo…     

Brazed Diamond Micropowder Bur Fabricated by Supersonic Frequency Induction Heating for Precision Machining

The common brazed diamond micropowder bur fabricated in a vacuum furnace produces an even brazing alloy surface. The small brazed diamond grits show low outcropping from the brazing alloy surface, and the chip space between them is small. The bur shows a low grinding efficiency and poor heat dissipation. In this study, a brazed diamond micropowder bur was fabricated by supersonic frequency induction heating. The method afforded a fluctuant surface on the brazing alloy. The brazed diamond grits with an outcropping height distributed uniformly on the fluctuant surface. The fluctuant surface showed a certain chip space. These characteristics of the tool increased the grinding efficiency and decreased the temperature of the grinding arc area. The roughness R _a of the ceramic tile surface trimmed by the tool cylinder was between 0.09 and 0.12 μm. In the first 90 min, the decrease in the weight of the ceramic tile ground by the tool cylinder was higher than that ground by the tool fabricated in a vacuum furnace. When the ceramic tile was cylindrically ground, the temperature of the grinding arc area measured using a thermocouple remained below 70 °C.     

细颗粒金刚石钎焊表面形貌与界面微结构

在加热温度900℃和保温时间8 min工艺下,采用钎焊工艺方法,实现细颗粒金刚石磨料与45#钢的牢固连接.运用扫描电镜、能谱仪检测了金刚石与钎料界面的微观形貌以及物相组成.试验表明:细颗粒金刚石在钎料表面实现均匀密集等高分布;在结合界面处形成了化合物,实现了金刚石磨粒与Ag - Cu - Ti合金之间的化学结合;钎料使...     

金刚石颗粒-金属粉末的CO2激光烧结机理研究

采用高功率横流CO2激光光束、60%Cu-15%Sn-10%Ni-15%Ti（质量分数）合金钎料和保护氩气在45^#钢板表面钎焊金刚石颗粒。研究了钎料厚度、激光功率、激光扫描速度、离焦量对钎焊层的影响,分析了钎焊层的微观组织结构,讨论了其冶金结合机理。结果表明：在激光功率850W、扫描速度9mm/s、光斑直径3mm、负离焦、激光钎焊粉料的厚度为0.5mm时,可获得金刚石颗粒、钎料合金、金属基体三者具有最佳结合性能的钎焊层;金刚石表面可能生成了TiC层,钎焊样品没有明显的缺陷,钎焊层、金刚石和钢板有较高的结合强度。     

钎焊单层金刚石砂轮的现存问题及其对策

概述了用活性钎料将金刚石磨料钎焊到钢基体表面制作单层金刚石砂轮 ,比传统的单层电镀金刚石砂轮具有明显的工艺优势。分析指出了钎焊工艺的现存问题 ,即如何实现金刚石磨料与合金钎料层高的结合强度、钎料层厚度的均匀性和金刚石磨料的有序排布。给出了可行的解决方案 ,即利用Ag -Cu -Cr或Ni-Cr等活性钎料与金刚石界面化学反应生成的Cr7C3 和Cr2 3 C7实现钎料层与金刚石间的高强度结合 ;通过砂轮地貌优化 ,优化出磨粒排布方式 ,然后按优化的结果排布磨料。研制出了具有磨料出露高度高、有序排布、钎料层厚度一致性、高结合强度、高锋利度的单层钎焊金刚石砂轮。     

CuSnTiNi钎料真空钎焊金刚石

采用两种不同比例CuSnTiNi混合单质金属粉,对金刚石在1 040℃保温5 min进行了真空钎焊试验.利用SEM,EDS及XRD对金刚石焊后界面微结构和钎料的微观组织进行了测试分析.结果表明,适合钎焊金刚石的活性成分为BCu70Sn15Ti10Ni5（质量分数,%）,该钎料能够在钎焊时首先合金化,在金刚石表面形成了断续的TiC,实现了金刚石的高强度连接,金刚石的热损伤较小,钎料组织由α-Cu固溶体、δ-Cu₃₁Sn₈等相组成,该钎料显微硬度为130~180 HV0.1,比CuSnTi有较高的硬度.     

Interfacial characteristics of titanium coated micro-powder diamond abrasive tools fabricated by electroforming-brazing composite process

In this study, abrasive tools were fabricated by an electroforming-brazing composite process. The abrasive tools were prepared using micro-powder diamond (MPD) grits with and without titanium (Ti) coatings. The interface characteristics of the MPD diamond grits and filler alloy were investigated. The results show that the diamond grits are uniformly dispersed on the surface of the steel substrate without visible agglomeration, and the NiCr filler alloy has good wetting toward diamond grits. Compared to the uncoated diamond grits, the abrasive grains with a Ti coating have an ideal grain distribution and brazed joints, and no aggregation of Si element observed at its edge. There is a more stable carbide TiC that formed on its surface in addition to the chromium carbide. Furthermore, the coated diamond grits are not graphitized and show a better residual stress state. In the abrasive tools with Ti-coated diamond, numerous intermetallic compounds (IMCs) are formed in the brazing layer, but the formation of theγ-Ni-based solid solution is relatively slight. The IMCs increase the microhardness of the filler alloy and help improve the wear resistance of the solder layer.     

钎焊金刚石耐磨涂层制备及其磨损性能

为提高农机刃具类零件的抗磨粒磨损性能,提出一种钎焊金刚石耐磨涂层制备方法,在Q235钢基体上制备了不同粒径及镀覆状态的金刚石耐磨涂层,并与65Mn钢的摩擦磨损和抗磨粒磨损性能进行对比。采用扫描电镜(SEM)对涂层表面、涂层与钢基体界面、涂层磨损后的表面微观形貌进行表征,并分析涂层的磨损规律及机理。结果表明:钎焊金刚石涂层与钢基体结合良好,金刚石在涂层中均匀分布,涂层厚度约370 μm。钎焊金刚石涂层的耐磨性优于65Mn钢的,且随着金刚石粒径减小钎焊金刚石涂层的摩擦系数降低,涂层的耐磨性增大;钎焊镀钨金刚石涂层的抗摩擦磨损和磨粒磨损性能均高于钎焊未镀覆金刚石涂层的。      

Microstructural characterization of diamond/CBN grains steel braze joint interface using Cu–Sn–Ti active filler alloy

In order to develop the new generation superhard abrasive tools of diamond and cubic boron nitride (CBN), the brazing joint experiments of diamond/CBN crystals and AISI 1045 steel matrix using Cu–Sn–Ti active filler powder alloy were investigated in vacuum furnace. The brazing temperature was 930 °C and the dwelling time was 20 min. Interfacial characteristics of the brazing joint among the diamond/CBN grains, the active filler layer and the steel substrate were analyzed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction techniques. The results indicated that Ti element in the Cu–Sn–Ti alloys diffused preferentially to the surface of diamond/CBN grits to form a Ti-rich reaction layer in the brazed joints by microanalyses. Moreover, the TiC, TiN and TiB₂ phases in diamond/CBN interface and Cu–Ti phase in steel interface were confirmed by X-ray diffraction phase analysis. The wetting and bonding reactions on diamond/CBN by melting Cu–Sn–Ti alloy were realized through the interfacial reaction products like TiC, TiN and TiB₂ compounds during the brazing process. The adhesive strength experiments of the joint interfaces revealed that the grains were not pulled out from the bond interface. The reliable bonding strength of brazed diamond/CBN grains to the steel substrate can meet the application requirements of high efficiency machining in the industrial field.     

Brazing diamond grits onto a steel substrate using copper alloys as the filler metals

Surface-set diamond tools were fabricated by an active metal brazing process, using bronze (Cu-8.9Sn) powder and 316L stainless steel powder mixed to various ratios as the braze filler metals. The diamond grits were brazed onto a steel substrate at 1050 °C for 30 min in a dry hydrogen atmosphere. After brazing practice, an intermediate layer rich in chromium formed between the braze filler metal and diamond. A braze filler metal composed of 70 wt % bronze powder and 30 wt % stainless steel powder was found to be optimum in that the diamond grits were strongly impregnated in the filler metal by both mechanical and chemical types of holding. The diamond tools thus fabricated performed better than conventional nickel-plated diamond tools. In service, the braze filler metal wore at almost the same rate as the diamond grits, and no pullout of diamond grits or peeling of the filler metal layer took place.     

提高钎焊金刚石工具质量的研究进展

详细地介绍了当前国内外钎焊工具的研究进展,主要包括:钎料组分选用,激光钎焊,表面镀覆金刚石的采用,钎焊工艺条件的优化,磨粒均匀/有序排布的实现,钎焊内应力的消除等,最后提出了目前亟待解决的问题。文中对众多的钎料合金,按照钎焊结合的实现原理,分成了两大类,即碳化钛类和碳化铬类,比传统的以合金组分划分显得更为简单而清晰。在新工艺方面着重介绍了采用激光束作为热源进行钎焊,激光钎焊加热速度快,能有效降低金刚石石墨化进程,而且能避免整体加热时工件易变形的特点。     

钎焊法制造单层金刚石取孔钻及其界面微观结构

使用钎焊法制造了单层金刚石取孔钻,并与电镀单层金刚石取孔钻的加工性能进行了比较.发现由于具有高的金刚石出刃和结合强度,钎焊取孔钻的锋利度和寿命都优于电镀取孔钻.通过光学显微镜、扫描电子显微镜(SEM)、能谱分析(EDX)和X射线衍射等对钢基体-钎料合金-金刚石的界面微观结构和成分进行了观察和分析,发现钎料合金中的Ni,Cr元素向钢基体中有一定的扩散;而在钎料合金和金刚石上分别存在反应层.钎料合金反应层主要是金刚石表面的C原子扩散进入液相后与Cr反应生成的Cr3C2和Cr7C3,而金刚石反应层是石墨化金刚石表面的位错通道与Cr反应形成Cr3C2并渗透到一定的深度形成的.     

基于钎料层厚度优化磨抛盘磨料粒度的仿真研究

采用热弹塑性有限元方法对钎焊金刚石磨抛盘真空钎焊过程进行建模与仿真,运用ABAQUS有限元分析软件,对其钎焊后冷却过程的瞬态温度场和应力场进行模拟,得出钎料层是影响磨抛盘钎焊后应力及变形量大小的重要因素。分析不同钎料层厚度时磨抛盘钎焊后的应力及变形量,合理确定在一定基体厚度情况下,钎料层厚度的最大值为0.2mm。结合钎料层厚度与磨粒高度的合理匹配关系,在理论上确定了钎焊金刚石磨抛盘可用的最大磨料粒度为30/35目。     

Investigation on the brazing mechanism and machining performance of diamond wire saw based on Cu-Sn-Ti alloy

Brazing connection between diamond particles and KSC82 carbon steel wire was established by the Cu-Sn-Ti alloy, and a diamond wire saw of 500 m in length and about 0.75 mm in diameter was fabricated. The brazing morphology of the diamond particles was observed using scanning electron microscopy (SEM), and the products and elemental distribution characteristics at the diamond brazed interface were analyzed by the energy disperse spectroscopy (EDS) and X-ray diffraction (XRD). The tensile mechanical properties of the brazed diamond wire saw was obtained through tensile tests, and the morphology of the fracture was observed using the SEM to analyze the tensile fracture mechanism. Further, the diamond wire saw was used for slice processing test of G663 granite, and the failure mode of the wire saw was analyzed. The results showed that there was Ti segregation at the diamond brazing interface, and that Ti₂C new phase was detected at the interface, where brazing connection of diamond particles was achieved through by reactive wetting. The tensile and yield strengths of the brazing diamond wire saw were 1289.08 and 923.18 MPa respectively, its plasticity was twice that of original KSC82 steel wire, and the tensile failure mode of the wire saw was ductile fracture. The stable cutting efficiency of the brazing diamond wire saw cutting the G663 granite with cross-sectional dimensions of 480 mm × 260 mm could reach 15 mm/min. There were three abrasive wear modes for the diamond particles of the wire saw working layer, including normal wear, shear fracture and separation, of which separation accounted for 14.3%. The reason for the separation of diamond was attributed to the oxidation of Ti element in Cu-Sn-Ti alloy and the fatigue crack initiation and growth at the diamond brazing interface.     

Brazing ferritic-martensitic reactor steels with an amorphous rapidly quenched nickel-based strip brazing alloy

A brazing alloy has been developed for brazing ferritic-martensitic steels. The technology for producing the brazing alloy based on nickel in the form of amorphous ribbons is described. Steels EP-450 DUO and EP-823 were brazed using the new brazing alloy. The relationships of the formation of brazed joints were determined. The results of brazing trials on models of fuel elements made of steels ChS-139 and EP-823 (EP-450 DUO) and the mechanical tests of the brazed joints (shear test) are presented.     

刃-孔协同分布钎焊金刚石微结构端面磨头加工氧化铝陶瓷性能的研究

由于高温钎焊金刚石的石墨化以及钎焊工艺等问题的限制,细粒度钎焊金刚石砂轮的制造还存在一定难度。提出一种刃-孔协同分布的钎焊金刚石微结构端面磨头,在粗粒度钎焊金刚石磨头上用脉冲激光刻蚀制备了不同的微结构,研究此钎焊金刚石端面磨头加工氧化铝陶瓷的磨削性能,对比不同微结构下的磨削力、被加工材料的表面质量以及金刚石磨粒的磨损特征。研究表明:与普通钎焊金刚石磨头相比,激光刻蚀的钎焊金刚石微刃磨头的磨削力和表面粗糙度分别降低了37%～51%和18%～25%,其中刃/孔数量比为1∶1的钎焊金刚石磨头的磨削力和表面粗糙度最低。      

银基钎料钎焊单层金刚石砂轮的研究

概述了单层高温钎焊超硬磨料砂轮的优点。这种新型超硬磨料砂轮以其卓越的磨削性能在今后将逐步替代传统电镀砂轮。鉴于它极其广阔的应用前景,国内也必将大力开发此种单层钎焊超硬磨料砂轮。本文利用高频感应钎焊的方法,用Ag-Cu合金和Cr粉共同作中间层材料,在一定的钎焊温度和时间下,实现了金刚石与钢基体间的牢固结合。经扫描电镜分析发现Cr与金刚石之间形成CrC,与钢基体之间形成（FexCry)C,这是实现合金层与金刚石及钢基体之间都有较高结合强度的主要因素。最后通过磨削实验证实了金刚石确实有较高的把持强度。     

高温钎焊立方氮化硼界面微结构

以Ag-Cu-Ti合金为钎料采用真空钎焊的方法在优化的钎焊温度和时间下，实现了立方氮化硼(CBN)与砂轮基体的牢固连接。运用扫描电镜(SEM)、X射线能谱仪(EDS)及X射线粉末衍射仪(XRD)对连接界面的微观组织以及CBN表面生成物的三维形貌、化学成分、物相结构进行了综合分析。结果表明，钎料中的元素Ti向CBN表面扩散富集，生成了针状TiB2和TiN，在磨粒与钎料界面形成化学冶金结合，这是CBN与Ag-Cu-Ti钎料间有良好浸润性和高结合强度的主要原因。磨削对比试验表明钎焊CBN砂轮比电镀CBN砂轮具有更高的磨粒把持强度。