金刚石与磨料磨具工程

Study on CBN-CBN bonding mechanism in high pressure infiltration sintering of PCBN

LIU Yinjuan, HE Duanwei

2016, 36(1): 1-5. doi: 10.13394/j.cnki.jgszz.2016.1.0001

Abstract(336)

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Abstract:
Study on CBN-CBN bonding mechanism in the high pressure infiltration sintering of polycrystalline cubic boron nitride(PCBN)was carried out in the CBN-Si system.In the present study,PCBN were sintered under high pressure and high temperature(HPHT)through infiltration method and mixed assembly method,respectively.The raw materials were sintered under 5.0-5.5 GPa,1300-1600℃ and 10-15 min by the assembly-methods mentioned above.The samples were analyzed through XRD,SEM,and hardness test.For CBN-Si system,results showed that CBN did not react with Si under the conditions of 5.0-5.5 GPa and 1300-1600℃ using either infiltration method or mixed assembly method.The samples sintered at 5.5 GPa and 1500℃ contained a large number of CBN-CBN bonding fabricated through the infiltration sintering process.PCBN with a much higher Vickers hardness could be obtain through infiltration sintering method at the same P-T conditions as compared to the mixed assembly method.The high pressure infiltration method was advantageous to plastic deformation and pore closing among the CBN grains,which could improve the densification of sintered samples.The grain-to-grain contact during compression would form local area with high stress,so as to promote molten Si layer infiltration CBN layer and fabricate CBN-CBN bonding among the CBN grain boundary.

Sapphire machined by SiC assisted fixed abrasive lapping

ZHU Lin, ZHU Yongwei, XU Sheng, LI Xinlu, SHEN Qi

2016, 36(1): 6-10,24. doi: 10.13394/j.cnki.jgszz.2016.1.0002

Abstract(365)

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Abstract:
Owning to insufficient self-conditioning ability affected by tiny chip,sapphire lapped by fixed abrasive pad is limited in industry.SiC particles were added to slurry to assist chips in conditioning pad in this study.Two different pads,one containing diamond abrasives(grain size 20-30 μm)and the other not,were made for experiment.The material removal rate and topography of sapphire at different conditions were compared to explore the influence of SiC on lapping process.Resultsshowed that the SiC particles added to slurry assisted in improving self-conditioning of pad by increasing wear of resins and exposing diamond abrasives out of sub-surface.Material removal rate of slurry with SiC particles was 14 times higher than that of slurry without SiC.

Parameter optimization of sapphire wafer lapping with fixed abrasive pad

ZHENG Fangzhi, ZHU Yongwei, ZHU Nannan, WANG Kai, SHEN Qi

2016, 36(1): 11-15. doi: 10.13394/j.cnki.jgszz.2016.1.0003

Abstract(333)

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Abstract:
In order to meet the requirements of the high processing efficiency and low damage of sapphire wafer,hydrophilic fixed abrasive lapping technology was adopted.The effects of silicon carbide particle size in matrix,matrix types,diamond particle size and abrasive in the slurry on material removal rate and surface roughness were investigated.The optimized process parameters for high material removal rate and good surface quality were obtained,which were 5 μm of SiC abrasive in the slurry,35-45 μm of diamond particle by company F,Ⅱof matrix type,10 μm of SiC particle size in matrix.The material removal rate could reach 413.2nm/min and average surface roughness R_a 0.140 2 μm.

Design and manufacture of thin and efficient diamond wire saw

LU: Yongan, HAN Jicheng

2016, 36(1): 16-19. doi: 10.13394/j.cnki.jgszz.2016.1.0004

Abstract(358)

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Abstract:
In view of economic requirement on cutting precious stones and other materials,a new type of diamond wire saw with ϕ2.0 mm and a new structure,is developed and produced.The new saw is used in marble cutting test to determine sawing parameters and implement performance analysis.Resultsshow that the new saw cuts sharply and is not easy to break.It is also shown that cutting speed of new saw is the same as that of the existing ϕ8.8 mm diamond wire saw.In addition,due to its small cutting seam,stone cutting yield can increase 20%-30% with lower power and less waste,which is energy saving and environment friendly.

Analysis on surface roughness in pre-stress hardening grinding process of 40Cr workpiece

LI Shengchao, WANG Yandong, WANG Yushi, ZHANG Xiuming, XIU Shichao

2016, 36(1): 20-24. doi: 10.13394/j.cnki.jgszz.2016.1.0005

Abstract(365)

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Abstract:
Surface roughness is an important index of surface integrity,which has a significant effect on the performance of mechanical parts.Pre-stress hardening grinding test was carried out on 40 Cr workpiece,during which characteristics and influence factors of surface roughness were studied.The surface roughness of initial,middle and final sections of the workpiece was respectively measured.Resultsshowed that the surface roughness of the workpiece was not uniform along the surface,and that it assumed a gradually increasing trend from initial section to the final.As pre-stress remained constant,the surface roughness of the workpiece increased gradually with the increase of cutting depth.However,as cutting depth remained constant,with the increase of pre-stress,the surface roughness decreased but the surface integrity of the workpiece increased.

MAX phase-diamond composites fabricated by microwave sintering

LIANG Baoyan, ZHANG Wangxi, WANG Yanzhi, XU Shishuai, WANG Junhe, YAN Shuaishuai, MU Yunchao

2016, 36(1): 25-30. doi: 10.13394/j.cnki.jgszz.2016.1.0006

Abstract(320)

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Abstract:
MAX ceramic bonded diamond composites were fabricated by microwave sintering from MAX phases and diamond raw powders.The effect of MAX phase and diamond content on phase and micro-structure of composites were studied.The result showed that different coating on the diamond could be obtained after microwave sintering.MAX phases'type and diamond had a different effect on the matrix composition and surface coating of diamond.Ti₂SnC might be obviously decomposed to Sn and TiC in the Ti₂SnC-diamond composites.When diamond content was lower,its surface was smoother.Additionally,small amount of circle organization were formed on the diamond.When diamond content was higher,many fine TiC grains were formed on the diamond.Ti₃AlC₂ may be also obviously decomposed to Al and TiC in the Ti₃AlC₂-diamond composites after sintering.Diamond was eroded obviously.Al₄C₃ and Al₂O₃ organization were formed on the surface of diamond.In Ti₃SiC₂-diamond system,the main phase of the matrix was Ti₃SiC₂.When diamond mass fraction was 10%,small amounts of Si,TiSi₂ and SiC were obtained.When diamond mass fraction was 20%,tiny TiC was obtained.SiC and TiSi₂ binary organization were formed on the diamond.

Influence of distance between filaments on preparation of diamond thick films

ZHAO Zhiyan, ZHOU Mingyu, HAO Chao

2016, 36(1): 31-33. doi: 10.13394/j.cnki.jgszz.2016.1.0007

Abstract(287)

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Abstract:
Diamond thick films are fabricated by hot filament chemical vapor deposition(HFCVD).The distance between filaments and enclosure are investigated to obtain high quality diamond thick films.By changing the distance between filaments and setting up enclosure,the growth rate can be up to 7.5 μm/h,and the thermal conductivity can be 1028 W/(m·K).The diamond films have dense structure and even let the red light through.

Research on precision grinding of ferrite with graphite grinding wheel

ZHANG Bei

2016, 36(1): 34-37,49. doi: 10.13394/j.cnki.jgszz.2016.1.0008

Abstract(341)

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Abstract:
Graphite white corundum grinding wheel was proposed in this test,which could meet the precision machining requests and simplify the process.The experiment indicated that when the grinding parameters were 24m/s of grinding speed,1-10m/min of workpiece speed,2.5-7.5 μm of cutting depth,the surface roughness of ferrite parts were below R_a 0.18 μm,and the best roughness could reach R_a 0.09 μm.Surface appearance was mirror-like.Consequently the grinding process could entirely meet the high surface quality requirement of ferrite.

Synthesis and characterization of ϕ58mm polycrystalline diamond compact

LI Sicheng, QU Jilai, FANG Haijiang

2016, 36(1): 38-42. doi: 10.13394/j.cnki.jgszz.2016.1.0009

Abstract(336)

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Abstract:
The polycrystalline diamond compact with 58 mm diameter was synthesized on domestic cubic press.Scanning acoustic microscope(SAM)analysis showed that there were no defects such as delamination,crack and non-uniform thickness of PCD layer in batch samples.Electrical conductivity and cutting test indicated that the cutting speed and wear resistance of the 25 μm grain size 58GD-025PDC and 58GM-253PDC with mixed grain size was superior to other competitors.

Study on dressing technology of super abrasive products

CUI Zhongming, HE Qingshan, FENG Chuangju, WANG Xing

2016, 36(1): 43-49. doi: 10.13394/j.cnki.jgszz.2016.1.0010

Abstract(396)

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Abstract:
Due to their superior grinding performances,super abrasive grinding wheel greatly promotes the development of grinding technology,especially in grinding difficult-to-process materials,high efficiency grinding and precision grinding.However,it is still in early phase of development and there are same key difficult problems which seriously restrict the application of super abrasive grinding wheel,one of which is dressing technology.Regarding the dressing of super abrasive grinding wheel,various effective dressing methods were analyzed and reviewed in this paper,including principles and characteristics.In the end,the future prospect on the development of dressing was described.

Research on domestic BARS cemented carbide anvil

PENG Wen, PENG Wei, KONG Defang

2016, 36(1): 50-56. doi: 10.13394/j.cnki.jgszz.2016.1.0011

Abstract(361)

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Abstract:
The basic principle of synthesizing of gem-grade diamond using pressless "split sphere" high-pressure apparatus(BARS)was introduced.The property of cemented carbide anvils placed in BARS was presented,as well as the industrializing process of Chinese cemented carbide for BARS.Research showed that using WC-Co ultrafine composite powder after stirring ball milling,cold isostatic pressing and low pressure sintering would increase the uniformity of organizational structure,together with compressive strength and elastic modulus of hard alloy.The optimum project to machine selflocalization anvil was to mutually act as reference and control product concentricity.Using M22/36 finishing wheel with a reasonable amount of feed in the grinding was the key to ensure the machining accuracy.

Influence of diamond parameters on cutting performance of diamond saw blade

ZHAO Jiong, CHEN Enhou, CHEN Feng, SHAO Qiang, SHAO Junyong

2016, 36(1): 57-60,65. doi: 10.13394/j.cnki.jgszz.2016.1.0012

Abstract(353)

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Investigations are made on diamond parameters,such as size,concentration and strength,based on filter cutting with metal bond blade to study the influence of these parameters on cutting performance of the blade,namely speed,chipping and blade life.The results show that as diamond size increases,cutting speed increases and then decreases while the maximum cutting speed is 10 mm/s with diamond size of 7-14 μm.It is also concluded that blades prepared with high-strength diamonds possesses higher cutting speed.In addition,high-strength diamonds would enhance blade life,and so will higher diamond size and concentration.On the other hand,diamond concentration should be 35%-50%to maintain good chipping performance.

Effect of Co on performance and structure of low-temperature Fe-based ceramic/metal composite bonds

MA Jiajia, HOU Yonggai, LI Guangfeng, TIAN Jiugen, ZHOU Qinghai, GAO Yuan

2016, 36(1): 61-65. doi: 10.13394/j.cnki.jgszz.2016.1.0013

Abstract(308)

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Abstract:
The effect of Co on performance and structure of low-temperature Fe-based ceramic/metal composite bonds was studied.Samples were sintered at 700℃in vacuum.Using mechanical tester,bending strength and impact strength of samples were tested and micro-topography analyzed using XRD and SEM.The results showed that when the addition of Co was 17wt%,it reacted with ceramic to form Co-CoO-ceramic cubic structure.The bending strength and impact strength of low-temperature ceramic/metal composite bonds reached their maximum,namely 130.55 MPa and 4.33 kJ/m²,respectively.The Fe-based prealloy powder with Co promoted finer bond crystalline,which reinforced the strength.

Effect of hot isostatic pressing on performance of diamond tools

ZHAI Xiangle, MENG Yunkai, CUI Hong, YIN Yuhang, TAO Hongliang

2016, 36(1): 66-69. doi: 10.13394/j.cnki.jgszz.2016.1.0014

Abstract(424)

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Abstract:
Research has been made to study the difference on mechanical property,such as density,hardness,impact strength,flexural strength and cutting performance,of Co powders which are sintered by hot isostatic pressing and traditional hot pressing.The results show that the relative density,impact strength,flexural strength and cutting performance of metal matrix sintered by hot isostatic pressing have been improved obviously.The hardness of the product is lower when sintered by hot isostatic pressing than that of traditionally sintered products.In addition,cutting tests show that diamond wire saw sintered by hot isostatic pressing performs well.

Grinding performance of Ni-coated diamond grinding wheel on cemented carbides

DING Yulong, ZHU Jianhui, XIONG Huajun, FENG Keming, DING Chunsheng, LI Shaojie

2016, 36(1): 70-73. doi: 10.13394/j.cnki.jgszz.2016.1.0015

Abstract(361)

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Abstract:
To study grinding performance of Ni-coated diamond and non-coated diamond,grinding tests on cemented carbides were conducted to compare the variations of grinding power,grinding ratio,surface roughness of workpieces and wheel surface.The results showed that in condition of using the same grinding parameters,Ni-coated diamond wheel required higher grinding power than non-coated diamond wheel did.Grinding ratio showed the same trend while ground surface roughness R_a was better when using the Ni-coated diamond.But there appeared more grinding chips and the grinding wheel tended to block up.

Analysis on surface integrity of GH4169 nickel-based superalloy ground with belt

SUN Chao, ZHANG Guojun, YIN Jiachao

2016, 36(1): 74-78. doi: 10.13394/j.cnki.jgszz.2016.1.0016

Abstract(323)

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Abstract:
Accumulated abrasive belt was used to grind nickel-based superalloy GH4169 at constant pressure.This method could control the pressure during grinding,so the impact of cutting force on grinding characteristics was reduced.By grinding nickel-based superalloy specimens through orthogonal experiment and range analysis,the optimal grinding parameters were obtained to gain the best surface roughness.The results showed that when the process parameters were grinding pressure 60 N,vibration frequency 1 Hz,and belt speed 34 m/s,the surface roughness would be R_a 0.072 μm,which reached its optimum.Meanwhile,the results verified the feasibility of this method and provided experimental basis for machining the material workpiece with suitable grinding parameters in production.

Thermal conductivity of diamond/copper composites prepared using powder metallurgy

ZHAO Yongzhi, LI Ying

2016, 36(1): 79-82,90. doi: 10.13394/j.cnki.jgszz.2016.1.0017

Abstract(428)

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Abstract:
To prepare material with higher thermal conductivity,new diamond/copper composite material was hot-pressed using powder metallurgy method with diamond and high purity copper powders.Orthogonal analysis was used to study the influencing factors of thermal conductivity of diamond/copper composite material.Resultsshowed that maximum thermal conductivity of new material was 245.89 W/(m·K)and that volume ratio of diamond to copper powders influenced thermal conductivity most. With the increase of volume ratio,thermal conductivity of diamond/copper composite material gradually decreased.Densification and interface bonding factor were important factors as well.Composite material with higher densification and better interface bonding possessed higher thermal conductivity and vice versa.

Study on polishing zinc selenide wafer

DONG Yunna, CAO Shuyun

2016, 36(1): 83-86. doi: 10.13394/j.cnki.jgszz.2016.1.0018

Abstract(290)

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Abstract:
Chemical mechanical polishing(CMP)method and self-made alumina polishing liquid were used to polish zinc selenide wafer.The polishing experiments were carried out for the influence of particle size of alumina polishing liquid,pH value,type and content of oxidizing agent on the surface state and removal rate of zinc selenide wafer.The results showed that alumina polishing liquid was suitable for the polishing and that the quality was better when the parameters were aluminum oxide particle size 200 nm(mass fraction of alumina 15%),soaked for 24 h with NaClO(mass fraction 3%)and pH value 8.The final removal rate was 2 μm/min and surface was smooth without scratches.

Design of ultrathin diamond tool powder feeding system

YUAN Jie, GUO Shuyi

2016, 36(1): 87-90. doi: 10.13394/j.cnki.jgszz.2016.1.0019

Abstract(315)

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Abstract:
In the manufacturing of ultrathin diamond tools by the press-sinter process,the distribution uniformity of diamond powder,matrix and alloy filler in the mold has a great impact on the finally using performance of the diamond tool.At present,domestic enterprises generally finish the mix by manually,which is difficult to meet the requirements of uniformity and consistency,so the quality of production and batch stability mostly are bad.Based on the research of distribution characteristics of particles in the tool mold,we designed an experimental device which could realize automatic mix of powders,and greatly improved the uniformity and consistency of the diamond tool forming materials,thus improving the durability of the tool,enhancing the market competitiveness of diamond tools,and reducing the use-cost of the buyer.

2016 Vol. 36, No. 1

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