In this study, a brazed diamond micro-powder grinding wheel with Ni-based filler metal was fabricated, which achieved one-step grinding forming of YG-6 cemented carbide rods. The interfacial microstructure, elemental diffusion behavior, and interfacial phases of the brazed diamond micro-powder joint were systematically characterized. Furthermore, the machining performance of the brazed diamond micro-powder grinding wheel was comprehensively evaluated in combination with its service life and the surface roughness of the machined YG-6 cemented carbide rods. The results show that the Ni-based filler exhibits good wettability to diamond micro-powder particles, and the diamonds have a reasonable protrusion height in the filler layer, with no graphitization observed on the surface of the brazed diamonds. During the brazing process, the active element Cr continuously segregates toward the diamond surfaces and reacts progressively with dissolved C atoms on the diamond surfaces, eventually forming a lath-shaped Cr-C compound layer on the diamond surfaces. XRD results identify this compound as Cr3C2. Elemental diffusion occurs between the filler layer and the steel substrate, forming a Fe-Ni solid solution diffusion zone. Consequently, the Ni-based filler forms a reliable chemical metallurgical bond with both the diamond micro-powder particles and the steel substrate. The as-prepared brazed diamond micro-powder grinding wheel exhibits excellent service life: a single wheel can grind more than 1300 YG-6 cemented carbide rods on average before failure. The surface roughness (Ra) of the machined YG-6 cemented carbide workpieces remains below 1.6 μm throughout all processing stages, which satisfies the requirements for one-step precision grinding.

To enhance the grinding performance and service life of rail grinding wheels, a novel brazed-resin composite wheel was developed by embedding brazed CBN (cubic boron nitride) segments into a resin working layer. The brazed CBN segments were fabricated using a Cu-Sn-Ti + WC (tungsten carbide) composite filler via a cold-press forming-vacuum brazing process. Microstructural and phase analyses revealed the formation of Ti-B and Ti-N compounds at the CBN-filler interface, indicating metallurgical bonding, while the incorporation of WC reduced excessive wetting, enabling precise shape retention of the segments. Comparative laboratory and field grinding tests were conducted against conventional resin-bonded wheels. Under all tested pressures, the composite wheel exhibited lower grinding temperatures, generated predominantly strip-shaped chips with lower oxygen content, and produced fewer spherical oxide-rich chips than the resin-bonded wheel, confirming reduced thermal load. Field tests demonstrated that the composite wheel matched the resin-bonded wheel in grinding efficiency, extended service life by approximately 28.8%, and achieved smoother rail surfaces free from burn-induced blue marks. These results indicate that the brazed-resin composite grinding wheel effectively leverages the superior hardness and thermal conductivity of CBN abrasives, offering improved thermal control, wear resistance, and surface quality in rail grinding applications.

The Ni-Cr-B-Si-W alloy brazing filler was used to braze steel substrate joints and TiC-coated diamonds in a nitrogen environment. The microscopic morphology of the bonding interface was then observed and analyzed. At a brazing temperature of 1115 degrees C, the TiC coating remained intact, which effectively protected the diamond surface from thermal damage under ultra-high temperature, demonstrating a novel prospect for brazing diamonds with high melting point alloy brazing fillers. After brazing, the molten brazing filler spread and diffused over the diamond surface, achieving chemical-metallurgical bonding with the diamond. The W-containing compounds grew between Cr3C2 and Cr7C3, accompanied by the formation of a small quantity of SiC, creating a new gradient reaction product morphology that contributed to the reduction of stress damage. Energy dispersive X-ray spectroscopy (EDS) surface scanning indicated that the titanium (Ti) element at the bottom of the TiCcoated diamond in contact with the brazing material was liberated. These liberated Ti elements reacted with carbon (C) elements to form new TiC. The generated punctiform TiC exhibited a growth tendency along the surface of the Cr-C compound. In some local regions, these punctiform TiC interconnected, ultimately forming a sheet-like structure.

To improve the thermal damage of brazed diamond joints, a Ni-Cr + Cu/C composite filler alloy was developed to replace the Ni-Cr filler alloy. In this paper, a detailed study was conducted on the influence of the addition amount of Cu/C particles on the microstructure and thermal damage of the joints. The results showed that a dense and orderly laminated Cr3C2 was formed on the surface of brazed diamond by Ni-Cr + Cu/C composite filler alloy, and the size of Cr3C2 decreased as the content of Cu/C particles increased. Cu/C particles dissolved during brazing, and the Ni-Cr + Cu/C composite filler layer was mainly composed of dispersed Cr-(B,C) compounds, Ni3Si and Ni (s,s). When the addition amount of Cu/C particles in Ni-Cr filler alloy was 3 wt%, Cu/C particles could effectively inhibit the interfacial reaction intensity and the generation of interfacial cracks. Cu/C particles could reduce the CTE mismatch between diamonds and Ni-Cr filler layer, and alleviate the surface erosion and surface graphitization degree. The Ni-Cr + Cu/C composite filler effectively mitigated the thermal damage and enhanced the impact strength of brazed diamond particles.

To address the issues of low grinding efficiency and the tendency of blockage and burning of the grinding wheel when working with ceramic materials using traditional resin and electroplated diamond grinding wheels, the feasibility of using brazed diamond technology to prepare a multilayer brazed diamond grinding wheel for ceramic grinding is analyzed. Combined with the optimization of filler metal composition, a multilayer brazed diamond grinding wheel with a slotted structure is prepared, and the grinding performance of 99.9% high-purity Al2O3 ceramics is tested. The results show that resin and electroplated diamond grinding wheels suffer from low grinding efficiency and insufficient grinding life, respectively. Single-layer brazed diamond grinding wheels exhibit high grinding efficiency but have limited grinding life. Multilayer brazed diamond grinding wheels show obvious advantages in terms of grinding life while maintaining high grinding efficiency, being about 60% higher than that of single-layer brazed diamond grinding wheels. During the ceramic material grinding process, the multilayer brazed diamond grinding wheel demonstrates remarkable grinding effectiveness. Despite the limited exposed height of abrasive particles, the slotting design significantly enhances chip removal, preventing the wheel's surface from bonding and blocking with ceramic powder.

Currently, the most common process for manufacturing brazed cubic boron nitride (CBN) tools is vacuum brazing using Cu-based active filler alloys. However, the high brazing temperature of Cu-based alloys and the long heating time in a vacuum furnace inevitably cause severe thermal damage, thereby compromising the mechanical properties of the brazed CBN abrasives. In this study, CBN abrasives were brazed using low-temperature Sn-Cu-Ti filler alloys in a continuous tunnel furnace. The final contact angles of the Sn-Cu-Ti filler alloys on the surfaces of the brazed CBN abrasives were determined at 650 degrees C. When the Ti content in the alloy was 4 %, the final contact angle was 37.2 degrees and the CBN maintained a good exposure height and achieved a firm holding force. The interfacial microstructure was analysed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). It was found that a layer of needle-like compounds, primarily comprising TiB2 and TiN, with an approximate thickness of 5 mu m, was formed at the interface, indicating the formation of a chemical-metallurgical bond between the Sn-Cu-Ti alloy and CBN abrasive. The residual stresses and mechanical properties of brazed CBN abrasives with Sn-Cu-Ti and traditional Cu-based alloys were measured and compared. The results showed that compared to the brazed CBN with the Cu-based alloy, the average residual stress of the brazed CBN with the Sn-Cu-Ti alloy was reduced by 25.2 %, while the compressive strength and impact toughness increased by 25.3 % and 13.8 %, respectively. The experimental results provide new insights into reducing thermal damage to CBN for improving the processing performance of brazed CBN tools.

Diamond grits were bonded to 1045 steel by Mo particles modified Ni-Cr composite filler. The effects of Mo particle addition on the morphology, bonding interface, residual stress, and diamond grits' strength were studied. The results show that: adding of Mo particles changed brazed diamond joints' morphology and interface element distribution. An appropriate amount of Mo particles reduced the distribution of interfacial cracks. The composite filler brazed diamonds generated two layers of compounds with different morphologies on the surface; the internal layer was a loose Cr3C2 layer, and the external layer was the Cr9Mo21Ni20 compound. The Mo particles could suppress the segregation of the active element Cr to diamonds, thus affecting the size and morphology of the interfacial Cr3C2 layer. The Mo particles effectively improved the CTE mismatch between the filler and diamond grits, but the excessive addition decreased the plasticity of the filler alloy. Ni-Cr + 4 vol% Mo composite filler brazed diamond joints have optimal morphology and lowest residual stress, while diamond grits have the best strength. Grinding tests showed that brazed diamond joints on diamond grinding heads fabricated by Ni-Cr + 4.vol% Mo composite filler exhibited the best fracture resistance.

The effects of Al2O3 content on the sintering behaviour, microstructure, and physical properties of Al2O3/vitrified bonds (SiO2-Al2O3-B2O3-BaO-Na2O-Li2O-ZnO-MgO) and Al2O3/vitrified bond cubic boron nitride (CBN) composites were systematically investigated using X-ray diffraction, differential scanning calorimetry, dilatometry, scanning electron microscopy, and X-ray photoelectron spectroscopy. Various amounts of Al2O3 promoted the formation of BaAl2Si2O8 and gamma-LiAlSi2O6, increasing the relative crystallinity of the Al2O3/vitrified composite from 85.0 to 93.2%, resulting in residual compressive stress on BaAl2Si2O8, thereby influencing the thermal behaviour and mechanical properties of the Al2O3/vitrified composite. The bulk density, porosity, flexural strength, hardness, and thermal conductivity of 57.5 wt% Al2O3 sintered at 950 degrees C were 3.12 g/cm(3), 6.1%, 169 MPa, 90.5 HRC, and 4.17 W/(m center dot K), respectively. The coefficient of thermal expansion of the bonding material was 3.83 x 10-6 degrees C-1, which was comparable to that of CBN, and the number of N-Al bonds were increased, which boosted the flexural strength of the Al2O3/vitrified CBN composite to 81 MPa. The excellent mechanical properties, compact structure, and suitable interfacial bonding state with the CBN grains of the Al2O3/vitrified composite make it a promising high-performance bonding material for superhard abrasive tools.

A kind of diamond abrasive grinding wheel was brazed in high vacuum furnace using Ni–Cr–P–Si active powder filler alloys. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectra and X-ray diffraction (XRD) technique analysis were applied to investigate the wear characteristics of brazing abrasive grinding wheel during the process of dry cutting ferrous metal and the interface characteristics of brazing diamond grains to steel substrate. The reaction products such as Cr7C3 and Cr3C2 carbides with columnar shape were formed toward around the diamond brazed interface. The results showed that diamond brazing abrasive wheel had an advantage in terms of more high efficiency and safety than resin grinding wheel during the process on cutting ferrous metals. The main tool wear model was abrasive grains broken, fracture and corrosion which were near the brazed interface. It revealed that the cutting chips were adhered to the surface of broken grains and covered the abrasive grits during the cutting process where arising high temperature on the grinding arc zone. Results proved that the graphitization phenomenon of diamond grits was slightly occurred and the diamond bonding strength was strong enough to meet the requirements of high efficiency and heavy load machining on dry cutting cast iron. The experiment also demonstrated that a kind of safety, high strength and super sharp diamond abrasive wheel could raise machining efficiency on cutting ferrous metal materials.

In order to alleviate the thermal damage and residual stresses of brazed diamond joints with Ni-based filler, W-coated diamond grains were used instead of conventional diamond grains and brazed onto 1045 steel substrates. The bonding interface properties, thermal damage and residual stresses of brazed W-coated diamond joints were investigated and studied. The results showed that the Ni-based filler exhibited good wettability to the W-coated diamond grains, and that the number and size of cracks at the bond interface of brazed W-coated diamond joints were significantly reduced compared with those of brazed conventional diamond joints. A dense and orderly Cr3C2 layer was generated on the surface of conventional diamond, while the disordered granular Cr3C2 growing into the filler alloy was formed on the surface of W-coated diamonds. With the isolation and protection of the coating, the brazed W-coated diamond grain surface has lower graphitization and better mechanical properties. At the same time, the thinner and more reasonable morphology of Cr3C2 layer on the surface of W-coated diamond effectively relieves the residual stress, and its maximum residual compressive stress is reduced by 9.43% compared with that of conventional diamond.

Ti containing Cu-based (TC) alloy reinforced glass-ceramic bond was fabricated for cubic boron nitride (CBN) abrasive tool materials, and its crystal composition, phase transformation, sintering activation energy, microstructure, element diffusion mathematical model, physical properties, and the bonding mechanism between the TC alloy reinforced glass-ceramic bond and the CBN grains were systematically investigated. The results showed that the structure, composition and sintering behavior of glass-ceramic were influenced by TC alloy adding. The generated TiO2 affected obviously the precipitation of β-quartz solid solution Li2Al2Si3O10, thus improving the relative crystallinity, mechanical strength and thermal properties. By establishing the mathematical model for element diffusion, the element diffusion coefficients of Ti and Cu were 7.82 and 6.98 × 10−11 cm2/s, respectively, which indicated that Ti diffused better than Cu in glass-ceramic. Thus, Ti4+ formed a strong Ti–N chemical bond on the CBN surface, which contributed to improving the wettability and bonding strength between CBN and glass-ceramic bond. After adding TC alloy, the physical properties of the composite were optimized. The porosity, bulk density, flexural strength, Rockwell hardness, CTE, and thermal conductivity of the composites were 5.8%, 3.16 g/cm3, 175 MPa, 90.5 HRC, 3.74 × 10−6 °C−1, and 5.84 W/(m·k), respectively.

In order to solve the problems of low grinding efficiency, easy to burn rail and large dust pollution, when grinding rail with traditional resin wheel, the feasibility of taking advantage of brazed diamond technique for preparing a new rail grinding wheel was studied. The brazed diamond grinding wheel with slotted structure was prepared by using of the diamond orderly arrangement process. The comparative grinding tests were carried out on U71Mn rail steel. The results show that compares with resin corundum grinding wheel, the new brazed diamond grinding wheel can improve the grinding efficiency by about 50%, effectively reduce the grinding temperature and avoid rail burn. The new grinding wheel has remarkable chip removal effect in the process of rail grinding, and there is almost no chip adhesion. However, the slots on the grinding wheel increases the grinding vibration, aggravates the breakage of diamond abrasive particles and increases the surface roughness of rail. The grinding debris of the new grinding wheel is mostly band-shape with large size but no molten balls.

To enhance the comprehensive bonding performance of brazed diamond joints, W-coated diamonds were developed instead of conventional uncoated diamonds. This study focused on the interface bonding performance of induction-brazed W-coated diamonds when used with Ni–Cr alloy. Under the influence of tungsten coating, the brazed W-coated diamond joints had an optimised bonding interface with a refined microstructure and significantly reduced interface cracks. The disordered and discrete morphology of the intermetallic compound Cr3C2 at the brazed W-coated diamond particle/Ni–Cr alloy interface alleviated the internal residual stress and the maximum residual compressive stress of the W-coated diamond joints by 16.35%. The degree of graphitisation and erosion of the W-coated diamond particles improved significantly. The brazed W-coated diamond bits exhibited superior processing performance. In the drilling process, the wear pattern of the W-coated diamond particles was dominated by mild particle micro-fractures rather than unfavourable particle macro-fractures or brittle intergranular fractures.

A novel brazing technology using a continuous tunnel furnace with modified Ni–Cr–W filler alloy is presented to achieve brazed diamond grinding wheels with high efficiency and low thermal damage. Mechanical characterization confirms that the static pressure strength and impact toughness of the diamond brazed using the new brazing technology are 22.2% and 10.5% higher, respectively, than those of diamond brazed using conventional vacuum brazing technology, respectively. Raman spectroscopy reveals that the degree of graphitization of diamond brazed with the novel brazing technology is decreased. In addition, residual stress is reduced by 23% after brazing with new brazing technology. Scanning electron microscopy is used to observe interfacial microstructure of brazed diamond. The elemental distribution and phase composition of brazed joint are analyzed by energy dispersive spectroscopy and X-ray diffraction. The results demonstrate that metallurgical bonds are formed between diamond and modified alloy, endowing strong bonding force to diamond abrasives. Tungsten (W) can react with diamond and modified alloy to form W–C compounds and bonding phases. Besides, W combines with certain amount of Ni element to reduce graphitization degree, improve integrity and decrease residual stress of brazed diamond. Compared with commonly utilized vacuum brazed grinding wheel, grinding test indicates that service life of grinding wheel, prepared by new brazing technology, is improved. The machining efficiency is increased by 42.4% and the abrasive invalidation rate is reduced by 33.7%. In conclusion, the diamond grinding wheel, prepared by new brazing technology, exhibits superior performance.

To improve the grinding and polishing efficiency and the heat dissipation effect, the distribution mechanism of abrasive grains on the grinding disc was studied, and the concept of regional landform optimization based on grinding and polishing conditions was put forward. Regional landform optimization showed that diamonds were uniformly distributed in inclined surface of the grinding disc and were densely packed on outer edges of the grinding disc. The landform of abrasive grains arranged in clusters of parabolic phyllodes can make the abrasive grains evenly distributed and have the best heat dissipation effect by phyllodes theory. The trajectory simulation of the abrasive particle arrangement of different landforms confirms this conclusion.

Under vacuum condition of 1 030 ℃ for 20 min, W-coated diamond was heated and brazed with Ni-Cr alloy powder. X-ray diffraction (XRD) was used to analyze the phase changes of W-coated diamond before and after heating. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to analyze the interface microstructure, the new phase, the morphology and that the element distribution. The results show that the coating phases of W-coated diamond change from W2C and W before heating to a large amount of WC and a small amount of W2C after heating, and that the coating does not fall off. After the W-coated diamond is brazed, there forms a small amount of NiW phase formed in the coating and the filler metal, the columnar Cr7C3 at the interface of W-coated diamond/Ni-Cr alloy, and the Cr-based intermetallic compound at the interface of steel substrate/Ni-Cr alloy.

In this study, the brazing of W-coated diamond to 1045 steel with Ni-based filler alloy was investigated. In addition, the brazing thermal damage of W-coated diamond joints was compared to that of uncoated ones. After brazing, the coating was not fount to affect the good wettability of the Ni-based filler alloy to the diamond. Moreover, the cracks at the interface of W-coated diamond were less and smaller. An ordered and compact Cr3C2 layer was formed on the surface of the uncoated diamond, while a disordered Cr3C2 layer and rod-like Cr7C3 growing into the filler alloy were formed on the surface of the W-coated diamond. The chromium carbide layer on the W-coated diamond surface was thinner, the graphitization degree was lower, and the maximum residual compressive stress was reduced by 11.4% compared to those on the uncoated diamond. The mechanical properties of the W-coated diamond grits were better preserved after brazing, and the coating alleviated the thermal damage of the brazed diamond joint.

To obtain the brazing effect of good exposure of abrasive particles and uniform thickness of the solder layer, the concept of vacuum brazing diamond with large particle size alloy solder was proposed, and the geometric model was established. The equation group of the relationship between large particle size alloy solder and diamond particle size was obtained, and the practical solution based on the wetting angle of alloy solder was obtained. In this study, NiCr alloy particles were used as the bonding agent and four sets of controlled experiments with different size combinations were conducted. The intermediate interface was analyzed by scanning electron microscopy and X-ray energy spectrometer. According to the test results, it demonstrated a large size NiCr alloy provides high consistency after brazing. Carbide chromium compound was also founded at the interface between diamond and alloy, which realized the firm control of diamond. This study showed that the new diamond brazing process based on the particle size matching mechanism was a feasible and promising method.

针对树脂砂轮打磨钢轨时存在的火花大、粉尘污染等缺点,设计并制作钢轨打磨用单层钎焊金刚石砂轮.通过钎焊金刚石砂轮和树脂砂轮的钢轨打磨试验对比,对钎焊金刚石砂轮的综合性能进行评价.试验结果表明:在稳定打磨阶段,相比树脂砂轮,钎焊金刚石砂轮的磨削效率高、磨削电流小、磨削火花小,打磨后的工件表面粗糙度好;钎焊金刚石砂轮的主要失效原因是磨屑黏附.

In view of the shortcomings of large spark and dust pollution in the grinding of rail with resin grinding wheel, a single layer brazed diamond grinding wheel used for rail grinding is designed and made. Through the grinding test, the comprehensive performance of the brazed diamond grinding wheel grinding rail is evaluated. Experimental results show that in the stable grinding stage, the grinding efficiency, grinding current and grinding spark of the diamond grinding wheel are better than that of the resin grinding wheel; the surface roughness of the workpiece after grinding by diamond grinding wheel is good, and the wear debris has no thermal deformation; the main reason of the failure of the diamond grinding wheel is the adhesion of the debris, and the abrasive particles have not been obviously worn out when they fail.