The Research On 3D Printing Of Diamond Particle Reinforced Tooling Materials

3D printing provides a novel idea for manufacturing diamond tools.At present,the 3D printing of diamond particle reinforced composites is still in the early exploration stage of processing optimization,densification mechanism investigation,microcrack control,and thermal damage evaluation etc.It is of great strategic significance to carry out related research for the development of diamond tools.Using selective laser melting(SLM)as the main additive manufacture technique and diamond-TC4 composite as the base material,this study constructed the relationship model between relative density of diamond-TC4 composite and SLM processing parameters through Response Surface Methodology,optimized the SLM processing parameters thereafter,and made microstructure analysis and mechanical property testing for SLM processed diamond-TC4 composites.Moreover,this study prepared Al₂O₃coated diamond powder by precipitation-coating process and investigated the SLM processing of Al₂O₃coated diamond-TC4 composites.It is found that:(1)The laser reflectivity for diamond-TC4 composites is low,therefore lower SLM laser power can effectively reduce the heat damage of diamond.(2)The relationship modelings between SLM processing parameters,including laser power(P,W),scanning speed(v,mm/s),and hatch spacing(h,mm),and relative density?for 5 diamond-95 TC4(Alloy#1)and 10 diamond-90 TC4(Alloy#2)are respectively:1#:r(28)-5.34868(10)0.047395P(10)0.003246v(10)4.65324h-0.000004Pv-0.01375Ph-0.00325vh-0.000109P²-0.000001v²-21.06287h² 2#:r(28)-11.84446(10)0.094515P(10)0.006782v(10)10.45725h-.0000009Pv-0.0275Ph-0.00175vh-0.000217P²-0.000002v²-93.74807h² Based on the relationship modelings,the optimum SLM parameters for Alloy#1 are laser power 195 W,scanning speed 1015 mm/s,and hatch spacing 0.04 mm and the optimum relative density is 98.9%,and the optimum SLM parameters for Alloy#2 are laser power193 W,scanning speed 1040 mm/s,and hatch spacing 0.045 mm,and the optimum relative density is 97.1%.(3)During SLM processing of diamond-TC4 composites,heat damage happened to diamond particles,resulting in partial graphitization of diamond surface and negatively affecting the densification of SLM processed parts.The degree of graphitization is not related to the diamond content.(4)Compared with TC4 alloy,SLM processed diamond-TC4 composites have higher Vickers hardness and wear resistance but lower bending strength and compression strength,which is mainly due to the low density and weak interface bonding between diamond and TC4.(5)During SLM processing of Al₂O₃coated diamond-TC4 composite,graphitization of diamond particles is significantly reduced due to the protection from Al₂O₃coating.(6)Vickers hardness on horizontal cross-section of SLM processed Al₂O₃coated diamond-TC4 composite is 453.4 HV and Vickers hardness on vertical cross-section is 446.9HV.The bending strength is 535.2 MPa and the compressive strength is 855.1 MPa.There is no apparent mechanical properties difference between Al₂O₃coated and uncoated diamond-TC4 composites,showing that Al₂O₃coating has no effect on mechanical properties of SLM processed parts.