Key Engineering Materials Vols. 359-360

Abstract: Brazing diamond grits onto steel substrate using a Ni-based filler alloy was carried out by laser beam in an argon atmosphere. The microstructure of the interfacial region among the Diamond grits, the filler layer and the steel substrate, were investigated by means of scanning electron microscopes (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). Meanwhile, the formation mechanism of carbide layers was discussed. All the results indicated that the active element chromium in the Ni-based alloy concentrated preferentially to the surface of the grits to form a chromium-rich layer, and the hard joint between the alloy and the steel substrate is established through a cross-diffusion of iron and Ni-based alloy.

Abstract: In this paper, two metal-bonded diamond wheels with different porosity were fabricated. The porosity of diamond wheel without additives of pore inducers is 7% and the wheel with pore inducers is 38%. Grinding experiments with these two grinding wheels on marbles were carried out under different grinding conditions. Experimental results revealed that highly porous grinding wheel has smaller grinding forces and better self-sharpening ability than the compact grinding wheel under the same grinding conditions.

Abstract: The Ti-coated diamond and the uncoated diamond were brazed with Ni-based filler alloy by high-frequency induction under argon atmosphere at 1050°C within 15 seconds. The interfacial microstructures between brazed diamond and the filler alloy were analyzed by scanning electron microscopy (SEM), energy dispersion spectrometer (EDS) and X-ray diffraction (XRD). It is surprisedly found that Cr-carbides forms normally and compactly on the surface of Ti-coated diamond brazed, whereas Cr-carbide forms tangentially and loosely on the surface of uncoated diamond brazed. The abrade experiment results for the brazed diamonds show that the bond strength between the normally formed Cr-carbide and the diamond is higher than that between Cr-carbide and uncoated diamond brazed. Furthermore, the cause that Ti changes the morphology of Cr-carbides on the surface of Ti-coated diamond brazed is discussed by the further tests specially designed.

Abstract: Plenty of studies on wear mechanism of diamond grains show that the specific failure form of single diamond grit has a close relationship with its load. Monolayer diamond grinding wheels and samples for shearing test are prepared by a high frequency induction brazing technique in this paper. The normal abrasion mechanism of diamond grains has been found through the comparison between the single grain tangential load during grinding and the shearing failure-load of the single grit of the test samples. The result shows that the dynamic strength of diamond grains is relative to the static strength after being brazed. Most of the grains are micro-broken during grinding, and only a few of them are pulled-out or broken-off.

Abstract: The bond in a grinding wheel cements the abrasive grains together, Among other factors, the bond plays a predominant part in the grinding wheel performances and on the quality of grinding results. This paper presents a literature review on organic bond grinding wheels. It discusses the characteristic of the bond and the grinding performances of the two mainly types of organic bond [1] grinding wheels: the resin bond grinding wheel and the soft-elastic grinding wheel. This paper provide a conclusion of the studying state of organic grinding wheel, which new studying can draw lesson from.

Abstract: To increase the manufacture efficiency of electroplated diamond tools, a nickel plating solution containing ammonium sulphate and sodium formate was investigated. The effects of concentration of ammonium sulphate, sodium formate and pH value on throwing power, covering power, ability to resist Cu2+ contamination and deposit microhardness were studied. Surface topography of deposits was also observed by SEM. Compared to watts bath, the plating solution studied is advantageous in terms of the performance of plating solution, deposit hardness and diamond bit behavior. Ammonium sulphate can refine deposit crystal grains and result in crystal form change.

Abstract: The present study was undertaken to compare the hardness and transverse rupture strength (TRS) of metal-based tooling composites containing diamonds of different grit sizes. Two kinds of bond matrix, copper-based and iron-based, were applied in the fabrication of the composites. In the copper-based matrix, rare earth was used as an additive. Diamonds of three different grit sizes were incorporated into two bond matrix, thereby forming six kinds of diamond composites. SEM and EDS were used to analyze the fractured surfaces of the composites. It was found that the diamonds of medium grit size in the copper-based bond matrix led to the highest hardness and TRS. For the iron-based bond matrix, however, the hardness and TRS of the composites containing the coarsest diamonds were found to be the highest. In same bond matrix, a close relationship between TRS and hardness was established.

Abstract: Finite element mode analysis and structure optimization of several multitude holes structure diamond saw blades are conducted to study vibration and noise of saw blade. Result shows multitude holes structure saw blade has lower natural frequency than conventional saw blade, which conduces decreasing of noise radiant efficiency. Through configuration optimization, it is clear that hole diameter, hole arrange group number and average displacement DMX of Z axes have great effects on saw blade vibration target function. Finally, the analysis to characters of sawing force and vibration by experiment helps to find out optimum structure of diamond saw blade with multitude holes, more rational sawing parameter and its adaptability to work piece material.

Abstract: Large advancements have been achieved in understanding nucleation and growth of CVD diamond, but adhesion of diamond film to substrates is poor and there is no good methods about how to quantitative evaluation of the adhesive strength. The blister test is a method appropriate for measuring the adhesion of CVD diamond. In this test a pressure difference is applied across a thin film and the pressure when the film separates from substrate is measured, and the adhesive strength of diamond thin film was calculated using analytical model. Using the finite element model, the deflection at the center of a free-standing window sample of diamond thin films is calculated as a function of applied pressure and the adhesive strength is obtained using the FEM. The result indicates that finite element method-based prediction of the total energy release rate is in good agreement with that obtained from analytical expressions and experimentally observed values.

Abstract: Ceramic is difficult to cut with normal machining method in precision intricate profile. The grinding process with diamond abrasive wheel is an effective process to machining ceramic materials. In this paper, a precise form-grinding method of ceramic materials with diamond grinding wheel is introduced. The tolerance of intricate profiler precision degree by this grinding process is less than 0.005mm. The machining process contains many techniques as high efficiency of profiler dressing technique of diamond wheel and form grinding process of ceramic. It gives some references on the developing of ceramic precision intricate profile machining techniques forward.