Characteristic And Application Of Iron-based Water Atomized Pre-alloyed Powder For Diamond Wire Saw

Diamond wire saw is a kind of flexible cutting tool with the main cutting part of bead,which is a powder metallurgical sintered body of diamond and metal bond.It is widely used in mining,cutting of stone scrap,arc-shaped slate and large slate.The key to the performance of wire saw is whether the diamond in the beads can be effectively controlled and continuously keep its cutting edge.There are two critical techniques that determine the performance of the bead:(1)The holding force of the sintered matrix with metal bond to diamond;(2)wear adaptability between the sintered matrix and diamond grits.Among all the metal binders,cobalt is the best material with comprehensive properties.Therefore,the development of diamond wire saw at domestic and foreign is mainly based on cobalt matrix.However,the expensive price of cobalt affects and restricts the development of diamond wire saw.So it is an urgent need for diamond wire saw industry to develop an iron-based binder to replace cobalt.At present,the following problems exist in iron-based binders,either in elementary powder system or in alloy powder system:(1)the wettability of matrix to diamond is poor,(2)the mechanical holding force of matrix to diamond is relatively low due to the poor alloying ability and low strength of matrix,(3)it is difficult to form stable chemical bond on diamond surface,(4)the sharpness is not good due to the insufficient cutting height of diamond,resulting from the strong wear resistance of matrix with coarsened grains after sintering at high temperature.1.In order to solve the above problems,a multi-component water-atomized prealloyed powder of Fe-Cu-Co-Ni-Sn alloy system,named as YA508,is successfully designed and prepared,which is mainly composed of Fe with the content of Co less than 30%.Through the design of element components and the quality control of the powder preparation,the above deficiencies of iron-based binders are overcome2.The matrix of cobalt powder sintered at 650-900?has good sintering density(94-96%),hardness(HRB104-108),bending strength(1600-1700MPa)and good wettability to diamond.The average grain size can be controlled within 20 microns of YA508 matrix sintered at 820~900?,and the sintered structure encapsulates diamond tightly.Besides,YA508 also shows excellent performance in a wide sintering temperature range,such as good sintering density(96-97%),hardness(HRB105-112),bending strength(1600-1900MPa),and these properties are equivalent to or higher than that of the cobalt-based matrix,thus,meeting the design requirements.3.The cold-pressed mixture of YA508 powder and diamond grit were sintered under the different conditions of vacuum,conventional hot press and high-temperature/highpressure(HTHP).The results show that the chemical bond is Fe3 C,and such chemical bond can effectively help to solve the common technical problems of poor holding force of iron-based matrix to diamond.Thus,the effective utilization rate of diamond increased and the comprehensive application efficiency of diamond tool is improved.4.Diamond wire saws with YA508 powder as main materials were produced to cut hard stones,and the cutting efficiency can reach 10-12 m2/h and the service life can reach 9-11 m2/m.Such efficiency of the as-produced diamond wire saw is the same as that of cobalt-based matrix,but the production cost reduces more than 60% compared with cobalt-based matrix,and YA508 powder has been applied on a large scale.