Ag-Cu-Ti钎料钎焊金刚石的界面微观组织分析

在真空炉中采用Ag-Cu-Ti钎料对金刚石磨粒进行了真空钎焊试验,实现了金刚石与钢基体的高强度连接.采用SEM对金刚石与钎料界面、金刚石表面碳化物形貌进行了观察分析,采用EDS分析了金刚石与钎料界面的成分变化,采用Raman对焊后的金刚石结构进行了分析.结果表明,Ag-Cu-Ti钎料中的Ti元素在界面处发生偏析,并在金刚石表面生成尺寸小于1 μm块状TiC,金刚石在焊接过程的高温中没有发生石墨化,最后在界面上形成了金刚石/TiC/钎料/钢基体的梯度结合层.     

细粒度金刚石钎焊热损伤的实验研究

采用Cr基钎料对细粒度金刚石在保护气氛下进行钎焊实验,通过SEM对金刚石与钎料界面微观形貌进行了观察分析,利用EDS分析了金刚石、钎料和基体三者之间化学元素的分布情况,借助Raman光谱分析了钎焊后金刚石颗粒的石墨化程度.结果表明:细粒度金刚石钎焊时,钎料爬升较高,钎料中的Cr元素向金刚石磨粒发生偏析,所使用的细粒度金刚石经过高温焊接后,有少许石墨化损伤.     

钎焊单层金刚石磨具的研究进展

钎焊单层金刚石磨具的研究和应用在国内外越来越受重视,与电镀单层金刚石磨具相比,钎焊单层金刚石磨具具有金刚石出刃高、容屑空间大、金刚石与基体之间的结合强度高等无可比拟的优点。从钎焊机理、钎料选择和钎焊工艺流程三方面介绍国内外钎焊单层金刚石磨具的研究现状,并分析大批量制造单层金刚石磨具存在的问题,指出下一步的研究有四项关键技术值得关注:钎料厚度的实用化控制、优质钎料的开发、钢基体受热变形、金刚石磨粒有序排布技术,为钎焊单层金刚石磨具的产业化提供借鉴。     

铜基钎料焊接金刚石的界面结构与强度

选用Cu-Sn-Ti活性钎料在钢基体上焊接金刚石磨粒,研究钎料合金与金刚石焊接界面的组织形貌与物相组成,分析不同钎焊温度对焊接界面结构及结合强度的影响.结果表明,钎料合金元素与金刚石在钎焊过程中发生化学反应,生成化合物TiC,CuTi和CuSn等,实现了铜基钎料、金刚石颗粒与钢基体之间的化学冶金结合.当钎焊温度为880～930℃时,均可获得连接良好的钎焊接头;钎焊温度900℃时,焊接界面形成的化合物层均匀连续且界面致密,此时在相同磨削条件下,钎焊金刚石试件的磨损失重很小,达到了焊接界面的强力结合.     

激光钎焊多层金刚石磨粒与镍铬合金的微观结合形态

在45钢基体上进行了镍铬合金钎料与金刚石磨粒的多层钎焊加工,借助光学显微镜、扫描电镜、能谱分析等研究了钎料与金刚石磨粒的结合形态、钎料层组织结构及其变化规律、金刚石表面损伤形态、金刚石与钎料结合处以及钎焊层的元素分布规律.结果表明:从与基体结合处到钎焊层表面分别形成了平面晶、胞状晶、树枝晶、柱状晶以及等轴晶的显微组织形态.输入的线能量影响钎料与金刚石的浸润结合、及钎焊层晶粒大小.逐道搭接钎焊时的热积累改变了搭接线附近的晶粒生长方向和大小,在逐层堆叠时的层与层结合线附近存在粗化晶粒区.金刚石磨粒的存在促使其周边形成等轴晶和垂直其界面生长的柱状晶和树枝晶.钎焊层内C元素含量在靠近上表面附近较高.钎焊层内部金刚石与钎料之间存在一元素过渡区域,Cr和Si元素在过渡区存在聚集现象,有利于形成Cr和Si的碳化物,促进金刚石与钎料间的冶金结合.钎焊层内的金刚石磨粒出现不同程度损伤及石墨化形态.     

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.     

空气中钎焊金刚石磨粒

利用活性钎料钎焊金刚石磨粒是一种新的金刚石工具的制造方法。采用高频感应钎焊的方法，用Ni—Cr合金粉末做钎料，适当的控制钎焊电流和钎焊时间，实现了金刚石与钢基体的牢固焊接。磨削实验表明用这种方法所制造的金刚石工具，金刚石磨粒与基体之间有着较高的结合强度，金刚石磨粒在整个加工过程中没有出现脱落的情况。     

Ag-Cu-Ti钎焊金刚石的界面结构及热应力分析

采用Ag-Cu-Ti钎料对金刚石进行真空钎焊实验,实现了金刚石与钢基体的高强度连接.采用SEM对金刚石与钎料界面、金刚石表面碳化物形貌进行观察分析,采用EDS分析金刚石表面碳化物的成分,利用XRD对焊后金刚石磨料的进行物相分析,采用Raman光谱对焊后的金刚石是否石墨化、残余应力进行分析.结果表明:Ag-Cu-Ti钎料中的Ti元素在界面处发生偏析,并在金刚石表面生成尺寸小于1μm的块状TiC.金刚石在焊接过程的高温下没有发生石墨化.金刚石中的最大拉应力位于磨粒顶部,为60 MPa,最大压应力在底部,为120 MPa.最后在界面上形成了金刚石/TiC/钎料/钢基体的梯度结合层.     

银基钎料钎焊金刚石的界面结构及TiC生长机制

在合适的工艺下,采用Ag-Cu-Ti钎料实现了金刚石与钢基体的高强度连接,并剖析了Ag-Cu-Ti钎料与金刚石的界面微区结构.通过对界面处的成分分布和深腐蚀后碳化物TiC形貌的观察,分析了Ti的作用机理、新生化合物TiC的形貌及生长规律.结果表明:在一定的条件下,Ti元素与组成金刚石的碳元素发生反应形成TiC层;碳化物层使钎料与金刚石之间产生冶金结合,并在其界面上形成了金刚石/TiC/钎料/钢基体的梯度结合层.     

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...     

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。     

Ni-Cr合金真空单层钎焊金刚石砂轮

单层高温钎焊超硬磨料砂轮具有传统电镀砂轮无法比拟的优异磨削性能 ,国内应及早研制开发应用此种砂轮。本文利用真空炉中钎焊的方法 ,用Ni Cr合金钎料 ,适当控制钎焊温度、保温时间和冷却速度 ,实现了金刚石与钢基体间的高强度连接。扫描电镜X射线能谱 ,结合金相及试样逐层的X射线结构分析 ,剖析了Ni Cr合金与金刚石和钢基体钎焊界面的微区组织结构 ;揭示了Ni Cr合金对金刚石和钢基体表面的浸润和钎焊机理。即在钎焊过程中会在金刚石界面形成富Cr层并与金刚石表面的C元素反应生成Cr7C3,在钢基体结合界面上Ni Cr合金和钢基体中的元素相互扩散形成冶金结合 ,这是实现合金层与金刚石和钢基体都有高结合强度的主要因素。最后重负荷磨削试验表明金刚石为正常磨损 ,没有整颗金刚石脱落 ,说明金刚石确有高的把持强度     

银基钎料钎焊单层金刚石砂轮的试验

概述了单层高温钎焊超硬磨料砂轮的工艺优势,这种新型超硬磨料砂轮 以其卓越的磨削性能在今后逐步替代传统电镀砂轮应是一种无法抗拒的必然趋势,鉴于它极其广阔的应用前景,国内在推广应用超硬磨料砂轮时也必将大力开发此种单层钎焊砂轮。本文利用高频感应钎焊的方法中,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,实现了金钢石和钢基体间的牢固连接,经X射线能谱及X射线衍射分析发现Cr与金钢石之间形成Cr3C2。这是实现合金层与金钢石有较高结合强度的主要因素,最后通过磨削试验证实了金钢石确实有较高的把持强度。     

Ni-Cr合金钎焊镀钛金刚石的研究

本文利用真空炉中钎焊的方法,采用Ni-Cr合金钎料,适当控制钎焊温度,保温时间和冷却速度,实现了镀钛金刚石与钢基体的高强度连接.并用深腐蚀处理钎焊后的试样,使金刚石脱离基体,用扫描电镜,X-射线能谱,对金刚石表面的碳化物进行了分析,剖析了Ni-Cr合金与镀钛金刚石的接口微区结构.结果表明:在钎焊过程中,钎料在金刚石表面形成富铬层并与金刚石表面的C元素反应生成Cr7C,和Cr3C2,其中Cr7C3呈笋状生长,Cr3C2呈片状生长,而Ti却并没有在表面形成碳化物.这主要是因为Ti元素与Ni的结合力大于Ti与C的结合力,因此,实现Ni-Cr合金与镀钛金刚石高强度冶金结合的,是活性钎料中的Cr元素.     

有序排布钎焊金刚石磨盘的实验研究

将有序排布理论运用到钎焊技术,成功制备适合黑色金属、钢铁材料磨拋的新型工具—有序排布单层钎焊金刚石磨盘;将平面单颗磨粒有序排布方式与磨料群可控排布方式相结合,设计出一种新型磨盘顶端平面排布方式,并确定排布参数;对船用钢板Q345低合金高强度结构钢进行磨拋试验,对比分析新型钎焊金刚石磨盘与传统树脂砂轮片的磨削性能。结果表明:新型磨盘较树脂砂轮片噪音提高,磨屑规则(主要呈带状),磨粒以磨损失效为主,几乎无整颗磨粒脱落,磨削效率约为树脂砂轮片的1.5倍。     

A study of grinding silicon nitride and cemented carbide materials with diamond grinding wheels

This paper presents selected results of the grinding of silicon nitride and cemented carbide materials with diamond grinding wheels, which will in later research be extended to the grinding of ceramic-cemented carbide compound drill tools. In these fundamental experiments four different types of diamond grinding wheels were used in face grinding processes. The diamond grinding wheels vary by the grain size, the grain concentration and the bonding material. The relevant influencing variables such as the cutting and feed speed and the coolant supply method were varied to investigate the effect on grinding of the two different workpiece materials, the brittle silicon nitride workpiece material and the ductile cemented carbide workpiece material. Some factors, which have significant effects, like the radial wear of the grinding wheel, the components of the grinding forces, the normal and the tangential grinding force, and the surface quality of the ground workpieces are discussed in detail.     

Study on the use of CuSnTi brazing alloy for induction brazing of diamond grits surface-treated by direct current plasma chemical vapor deposition

Induction brazing of diamond grits surface-treated by direct current plasma chemical vapor deposition (DC-PCVD) on a steel substrate was carried out in an argon atmosphere. A CuSnTi brazing alloy (with an approximate melting temperature of 900 °C) was used for this purpose. The diamond edges were exposed out of the brazing alloy to retain their sharpness. Relatively fine titanium–carbon compounds were formed with uniform interspaces on the brazed diamond surface when immersed in the brazing alloy. The liquid brazing alloy filled the interspaces, leading to increased bonding strength between the brazing alloy and diamond grits. Boring tests on diamond core drills brazed with the treated diamond grits and untreated diamond grits showed that the percentages of whole grain fracture and of pullout from the matrix of the brazed treated-diamond grits became lower.     

3D laser investigation on micron-scale grain protrusion topography of truncated diamond grinding wheel for precision grinding performance

A grain tip (GT) truncation is proposed to truncate grain protrusion tips of #270 diamond grinding wheel in plunge grinding of hard and brittle material. In this study, a 3D laser microscopy was employed to measure the wheel working surface and parameterize its 3D grain protrusion topography. The objective is to investigate how micron-scale grain protrusion parameters influence grinding performance such as grinding force and surface roughness. First, the GT truncation was performed after dressing of diamond grinding wheel in grinding experiment of quartz glass; then its 3D grain protrusion topography was constructed by smoothing 3D measured noise, matching measured point cloud, transferring protrusion frame and extracting 3D diamond grains; finally, the grain protrusion parameters such as grain protrusion number, grain protrusion height, grain protrusion volume, grain rake angle, grain clearance angle, etc. were investigated in connection with ground surface and grinding force. It is shown that GT truncation averagely decreases grain protrusion number, grain protrusion height, grain protrusion volume, grain rake angle and grain clearance angle by about 44%, 74%, 75%, 24% and 70% on whole wheel surface, respectively. However, it greatly increases active grain number by about 32 times and active grain volume by about 181 times in actual grinding with the depth of cut in 1 μm, thus leading to a decrease (about 80%) in surface roughness and an increase (about 40 times) in grinding force. It is also found that truncated diamond grain tips are mostly shaped with nanometer-scale tip wedges along grain cutting direction, leading to about 75% very large negative grain rake angles and about 75% large grain clearance angles, thus contributing to ductile-mode grinding. It is confirmed that the active grain number and active grain volume for the actual depth of cut may be regarded as main grain protrusion parameters to evaluate and predict the precision grinding performance of a coarser diamond grinding wheel.