Bismaleimide Modified by Allyl Novolak for Superabrasives

A novel thermosetting resin system for superabrasives based on novolak and bismaleimide （BMI） was developed. The novolak resin was allylated and then copolymerized with BMI. The structure of allyl novolak and reaction mechanism were analyzed by FFIR. Thermal and mechanical properties were characterized by using com- prehensive thermal analyzer （DSC-TG） and strength tester, respectively. The results showed that high molecular weight of novolak was advantageous for heat-resistance, but was unfavorable for the bending strength. High allyl content improved the heat-resistance but lowered the bending strength. When the molecular weight of novolak was 450 and allyl content was 50%, the best resin system with good heat-resistance and bending strength was obtained. It was suitable for the manufacturing of superabrasive tools.

Review on monolayer CBN superabrasive wheels for grinding metallic materials

A state-of-the-art review on monolayer electroplated and brazed cubic boron nitride（CBN） superabrasive wheels for grinding metallic materials has been provided in this article. The fabrication techniques and mechanisms of the monolayer CBN wheels are discussed. Grain distribution, wheel dressing, wear behavior, and wheel performance are analyzed in detail. Sample applications of monolayer CBN wheel for grinding steels, titanium alloys, and nickel-based superalloys are also provided. Finally, this article highlights opportunities for further investigation of monolayer CBN grinding wheels.

Mist-jetting Electrical Discharge Dressing Technology for Superabrasive Grinding Wheels

The technology of superabrasive grinding has been developed in order to achieve high-quality finish in extremely hard and brittle materials.Thereafter, truing and dressing technology on super abrasive grinding wheel is one of the most important subjects on precise machining field at present.In this paper, mist-jetting electrical discharge technology was applied to dressing metal-bonded superabrasive wheels.And a systematical study on the mechanism of selective removal of the bond was proposed.Experiments on dressing bronze bonded diamond grind wheels were carried out on a die-sinking electrical discharge machine.The diamond wheel topographies before and after electrical discharge dressing were observed by VH-800 3D digital microscope.The wheel profiles before and after dressing were observed.The results of electrical discharge dressing under different electrical parameters were compared.Experimental results indicate that the favorable surface topography can be obtained under suitable processing parameters and mist-jetting electrical discharge dressing(MEDD) is feasible for metal-bonded diamond grinding wheel.

Ultrahigh pressure sintering of polycrystalline diamond cubes

Polycrystalline grits(polygrits) have been used widely in industry as abrasives.Due to their higher impact strength and the friable nature,polygrits are more endurable and more efficient than monocrystal grits (monogrits) in material removal applications.For example,polygrits of alumina may last longer and cut faster than monogrits.Similarly,polygrits of cubic boron nitride is a superior superabrasive than monogrits of the same. Although diamond superabrasives have been indispensable for constructional sawing applications and industrial grinding applications,there has no polygrits of diamond that are commercially available.In this research,we used a novel technology to sinter micron diamond fines to form polygrits of diamond.The characterization demonstrated that polygrits of diamond can be tough to withstand impact.But due to the presence of micro grains,the grit can sharpen itself without dulling by shedding the worn grains.This paper revealed many examples of using diamond polygrits.

Remarkable achievements,splendid future——Celebrating the 45^(th) anniversary of synthetic diamond of China

The development of China as the world’s manufacturing house is best exemplified in the industry of diamond superabrasives.Diamond is indispensable in the creation of industrial infrastructure,including the construction of roads and building of houses.The world’s diamond was provided mainly by countries outside China in last century.However,a"great leap forward"has taken shape with rapid expansion in Chinese diamond-making capabilities from the enlargement of the equipment(cubic presses) and improvements in diamond yield and product quality in the end of last century.At the turn of this century,China outpaced the rest world combined in the total diamond output,became the largest producer in the world indubitably.In 2007,China produced nearly 4.4 billion carats,80%of the world’s diamond total output.The Chinese diamond well accepted in the world can be seen in the export statistics of China & import statistics of developed countries in this paper.For example,59%of USA imported diamonds were from China in 2007;in Japan, 40%. This report contains a survey of some main industrial sectors that use diamond superabrasives.Overall,22 tables and figures are used to portray the many facets of superabrasives,including cubic boron nitride.The report also discusses several challenges facing Chinese diamonds,such as the vast price difference between imported diamond grit produced outside China and domestic supply.This paper also presents an outlook of the future development of the Chinese superabrasives industry basing on the Chinese macroeconomics and the recent data of the end-users as well as their future development trend.The paper concludes by proposing that although remarkable achievements have been made in the past 45 years,given the fact that Chinese superabrasives industry still lags behind that from the advanced countries on a multitude of variables,further endeavor should be made to make China a super country in the superabrasives industry in the world.