Diamond grits are indispensable for sawing granite or concrete.Each year about 1 000 tons of diamond grits are consumed for such purposes.In all cases,mono crystalline diamond is used.However, polycrystalline grits(po...Diamond grits are indispensable for sawing granite or concrete.Each year about 1 000 tons of diamond grits are consumed for such purposes.In all cases,mono crystalline diamond is used.However, polycrystalline grits(polygrits) are generally better performed than mono grits as abrasives.For example,poly grits of cubic boron nitride(e.g.Borazon(?) CBN-550 of Diamond Innovations) can cut faster and they last longer than mono grits(e.g.Borazon(?) CBN-500). Polygrits of alumina(e.g.Cubitron(?) of 3M) also out perform by far glassy grits(e.g.white alumina).For diamond superabrasives,micron polygrits formed by shock waves may polish as fast as mono grits of the same size,but without causing as much scratches due to the presence of smaller sintered grains.The improved performance of poly grits is attributed to their ability to micro chipping that renews the sharp cutting corners from time to time.By contrast,mono grits tend to round off at low cutting force or macro fracture at high cutting force,so they may lose the cutting ability rapidly. For sawing granite with mesh sizes 40/50 or coarser,poly grits of diamond have not been available until recently.In this research,we have made polygrits in mini cube with sizes of 18/20,20/25,and 30/40.Turbo grinders and wire saws were made by brazing both mono grits and polygrits on steel substrates.Cutting performance on granite demonstrated that grinding speed was faster with turbo grinder,and the surface finish was smoother with wire saw for poly grits than mono ones. Polygrits and mono grits of diamond were mixed for comparison(upper left).Polygrits of mini cubes were brazed on the pearl of a wire saw(upper right).Mono diamond grits were brazed on a turbo grinder(bottom diagrams ).展开更多
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 (monogr...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.展开更多
Diamond grits may be thermally weakened during the high temperature cycle of brazing.This weakening may exhibit as diamond breakage.During the dressing action,taller diamond grits are more likely to break due to the h...Diamond grits may be thermally weakened during the high temperature cycle of brazing.This weakening may exhibit as diamond breakage.During the dressing action,taller diamond grits are more likely to break due to the higher stress present.展开更多
文摘Diamond grits are indispensable for sawing granite or concrete.Each year about 1 000 tons of diamond grits are consumed for such purposes.In all cases,mono crystalline diamond is used.However, polycrystalline grits(polygrits) are generally better performed than mono grits as abrasives.For example,poly grits of cubic boron nitride(e.g.Borazon(?) CBN-550 of Diamond Innovations) can cut faster and they last longer than mono grits(e.g.Borazon(?) CBN-500). Polygrits of alumina(e.g.Cubitron(?) of 3M) also out perform by far glassy grits(e.g.white alumina).For diamond superabrasives,micron polygrits formed by shock waves may polish as fast as mono grits of the same size,but without causing as much scratches due to the presence of smaller sintered grains.The improved performance of poly grits is attributed to their ability to micro chipping that renews the sharp cutting corners from time to time.By contrast,mono grits tend to round off at low cutting force or macro fracture at high cutting force,so they may lose the cutting ability rapidly. For sawing granite with mesh sizes 40/50 or coarser,poly grits of diamond have not been available until recently.In this research,we have made polygrits in mini cube with sizes of 18/20,20/25,and 30/40.Turbo grinders and wire saws were made by brazing both mono grits and polygrits on steel substrates.Cutting performance on granite demonstrated that grinding speed was faster with turbo grinder,and the surface finish was smoother with wire saw for poly grits than mono ones. Polygrits and mono grits of diamond were mixed for comparison(upper left).Polygrits of mini cubes were brazed on the pearl of a wire saw(upper right).Mono diamond grits were brazed on a turbo grinder(bottom diagrams ).
文摘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.
文摘Diamond grits may be thermally weakened during the high temperature cycle of brazing.This weakening may exhibit as diamond breakage.During the dressing action,taller diamond grits are more likely to break due to the higher stress present.
