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Quick Search     Adv Search   2022 Vol. 32, No. 05 Published: 2022-10-10   1 Research progress in preparation of high thermal conductivity copper matrix composites by powder metallurgy Hot! BAO Rui，LI Zhaojie，YI Jianhong，TAO Jingmei，GUO Shengda DOI: 10.13228/j.boyuan.issn1006-6543.20210157 With the rapid development of network communication, the increase of the unit heat production power of electronic chips puts forward higher requirements on the heat dissipation capacity of thermally conductive mate‐ rials. Traditional metal thermally conductive materials can no longer meet the requirements for use, and it is immi‐ nent to develop new thermally conductive materials. The copper matrix composite material with excellent thermal conductivity and mechanical properties is used as the matrix, and the copper matrix composite material obtained by adding the reinforcement with high thermal conductivity and low expansion can take into account the characteris‐ tics of adjustable thermal expansion coefficient and high thermal conductivity. Based on the common characteris‐ tics of high thermal conductivity and low expansion, copper-based composite materials such as carbon material/ copper, silicon carbide/copper, diamond/copper, etc. are widely used as ideal heat dissipation materials in the fields of semiconductor preparation, aerospace, and military defense. The types of reinforcements are classified, focusing on the research progress of copper matrix composites with diamond, graphene, graphite, carbon nanotubes and SiC as reinforcements in recent years, and the current problems and problems of high thermal conductivity copper ma‐ trix composites. Future research directions are prospected. 2022 Vol. 32 (05): 1-11 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 12 Flow field characteristics and particle flow characteristics of atmospheric plasma spraying Hot! ZHANG Yong，GUO Longlong，JU Luyan，WU Heng DOI: 10.13228/j.boyuan.issn1006-6543.20210110 Numerical analysis combined with experimental research method has been used to study the flow field characteristics and particle flow characteristics of atmospheric. The results show that the spraying temperature of argon hydrogen mixture is higher than that of pure argon about 30%. Particles temperature and velocity are lower than those of the main gas when spraying distance is less than 70 mm, so particles are in the process of heating speed up. Particles temperature and velocity are reached the highest, close to the main gas when spraying dis‐ tance is between 70-90 mm. Main gas temperature and velocity are lower than those of particles when spraying distance is greater than 90 mm, so particles are in the process of cooling speed down. The experimental results show that the particle velocity and temperature calculation value and experimental value have the same change trend, verifying the accuracy of the results of numerical calculation. Flow field temperature and velocity increases with the increase of main gas when the main gas flow is constant. Fluid velocity increases with the increase of the main gas. Flow field temperature decreases with the increase of the main gas. 2022 Vol. 32 (05): 12-18 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 19 Design and preparation of ZrO2/stainless steel composite with different electrical conductivity Hot! LAI Xuping，LIU Xili，WANG Lianghui DOI: 10.13228/j.boyuan.issn1006-6543.20210141 Ordinary materials are not compatible with good conductivity and mechanical properties, using 316L stainless steel powder and ZrO2 powder as raw materials, the gradient ZrO2/316L composite materials with the volume fraction of 50%, 60%, 70%, 80% and 90% of 316L stainless steel powder were prepared by vacuum hot pressing sintering method, respectively. The results show that the composite is a ceramic matrix composite when the sintering temperature is 1 300 ℃ and the volume fraction of 316L is 50%. When the volume fraction increas‐ es to 60%, the composite starts to form a 316L skeleton, and as the volume fraction of 316L increases, its internal stainless steel morphology changes from diffusely distributed independent spheres to linked in sheets and eventu‐ ally becomes a metal matrix composite. The hardness and resistivity of the composites decrease with the increas‐ ing volume fraction of 316L. 2022 Vol. 32 (05): 19-23 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 24 Development of high energy and high power density wet Cu-based friction material Hot! Lü Bo，WANG Sanquan，LIN Haosheng，ZHOU Juying DOI: 10.13228/j.boyuan.issn1006-6543.20210062 The friction and wear properties of wet Cu-based friction material could be improved by the develop‐ ment of a wet Cu-based powder metallurgy friction material of high-energy and high-power density, which is, af‐ ter composition designing and process optimization, manufactured by the powder metallurgy technique, with the addition of alloy elements such as Sn, Zn, Ni and Ti as the alloy components, flake graphite and artificial graph‐ ite of different particle morphologies and particle sizes as the lubricating components, and ZrO2 as the friction components. The result shows that the friction coefficient, stability, hardness of Cu-based friction material could be improved significantly with addition of Sn, Zn, Ni, Ti and other multicomponent alloy elements in the matrix. The stability of friction coefficient at high speed is strengthened obviously with the addition of ZrO2, the heat re‐ sistance is evidently reinforced with the addition of a large proportion of flake graphite and artificial graphite. Such additions and process optimization can effectively raise the energy absorption and power level of friction materials, the allowable value of energy load increases by 30%, the friction coefficient is high and stable, and the wear rate is significantly lowered. 2022 Vol. 32 (05): 24-30 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 31 Differential thermal analysis of porous NiTi alloy prepared by powder metallurgy Hot! LIN Yuebin，LIU Aihui，ZHUANG Zhiping DOI: 10.13228/j.boyuan.issn1006-6543.20200291 With the help of scanning electron microscope and differential thermal analyzer, the microstructure and reaction temperature of Ni-Ti mixed system under different heating rates were studied, and the effect of heat‐ ing rate on the chemical reaction process of Ni and Ti was investigated. The reaction kinetic parameters of Ni-Ti mixed system were calculated by Kissinger equation, in order to further regulate the chemical reaction between Ni and Ti in the process of powder metallurgy and prepare high-quality porous NiTi shape memory alloy. The re‐ sults show that with the increase of heating rate, the chemical reaction of Ni-Ti mixed system is significantly en‐ hanced, and the reaction heat release is significantly increased, but the initial reaction temperature changes little. The reaction activation energy of Ni-Ti mixed system is 130 kJ/mol, and the reaction rate constant is 5.6×10-3, the reaction order is 1.26. 2022 Vol. 32 (05): 31-35 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 36 Process optimization and properties of NiFe2O4 ceramics prepared by spark plasma sintering Hot! YAN Liang，YAN Biao DOI: 10.13228/j.boyuan.issn1006-6543.20210070 ingle phase NiFe2O4 ceramics were prepared from NiFe2O4 powder with particle size of 50 nm. The spark plasma sintering process was optimized. The effects of heating rate and holding time on the phase, micro‐ structure, density and magnetic properties of sintered blocks were studied. The results show that the heating rate increases from 30 ℃/min to 60 ℃/min, and the density increases significantly to 97.7%. When the heating rate increases by 100 ℃/min, the density increases to 98.3%, and the hysteresis loss decreases with the increase of heating rate; When the holding time is extended from 4 min to 12 min, the permeability and density of the block increase, but when the holding time exceeds 12 min, the density and permeability do not increase but decrease. The results show that the optimum sintering process is heating rate of 100 ℃/min and holding time of 12 min. The density of NiFe2O4 ceramic sintered body is 98.3%, the permeability is 13 000 H/m. 2022 Vol. 32 (05): 36-40 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 41 Effects of ZrO 2 powder content on MAO film characteristics of AZ91D magnesium alloy Hot! ZHAO Haoyu，CHEN Weidong，LIU Shuo，LI Jintao DOI: 10.13228/j.boyuan.issn1006-6543.20210115 In order to improve the properties of micro arc oxidation (MAO) coating on AZ91D magnesium alloy, the MAO coating with different ZrO2 powder content in electrolyte was prepared on AZ91D magnesium alloy. The surface morphology, roughness, thickness and corrosion resistance of the coating samples were characterized. The results show that with increasing of the content of ZrO2 powder from 0.5 g/L to 2.5 g/L in the electrolyte, the roughness of coated surface increases from 2.0 μm to 3.3 μm, the thickness of surface layer decreases from 115 μm to 85 μm. SEM-EDS mapping results show that the films are mainly consist of O, Mg, Al, Si and Zr ele‐ ments. The microcracks on the surface of the MAO coating decrease significantly when ZrO2 content in electro‐ lyte are more than or equal to 1.5 g/L. When the addition amount of ZrO2 is 2.0 g/L, the corrosion current density of the coating is the smallest and the corrosion resistance is the best, which is only 0.93 μA/cm2. 2022 Vol. 32 (05): 41-45 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 46 Modification mechanism and CO denitration activity of V/AC catalyst Hot! LI Jianli，HUANG Bangfu，WANG Zhuo，WEN Zhenjing，LI Wanjun DOI: 10.13228/j.boyuan.issn1006-6543.20210097 In order to investigate the modification mechanism of activated carbon with different vanadium loads and the CO denitration activity of the prepared catalyst, coconut shell activated carbon was selected as catalyst carrier in this paper. A series of V/AC catalysts were prepared by using nitric acid activated, impregnation with VOSO 4 solution, and calcination. V/AC catalysts were characterized by SEM, EDS, BET, XRD and FTIR. V/AC modification mechanism was researched. The results show that the surface active components of the catalyst con‐ tain Vanadium and Vanadium oxide. The pore volume of activated carbon is efficiently utilized with 10%V loading catalyst. A new structure is formed and the specific surface area and pore volume are increased with the 10%V load‐ ing catalyst. The active components of V2O5 and V2O3 is observed on the surface of V/AC catalysts. The carboxyl group and O-H functional group decrease gradually with the increase of V loading capacity, too much vanadium can break the C-OH, C-O and C=O bonds. The denitration activity of 10%V loading catalyst with better physical and chemical parameters is higher than others. The CO denitration activity of 15% V loading catalyst is higher than 5%V loading catalyst's. The research results can provide reference for the preparation of low temperature catalysts and the application of CO denitration technology. 2022 Vol. 32 (05): 46-51 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 52 Study on microstructure and properties of high borated steel Hot! PEI Yanbin，WANG Tiejun，GE Qilu，QU Xuanhui DOI: 10.13228/j.boyuan.issn1006-6543.20210038 High borated steel with boron content of 1.04%, 1.50% and 1.9% were prepared by powder metallurgy and casting process. The microstructure, phase, distribution of boron element and their effects on the properties of the alloy were studied. The results show that the distribution of boron element in the alloy prepared by powder metallurgy is uniform, while the boron element in the casting alloy segregated at the grain boundary, so the plas‐ ticity of the alloy prepared by the former is obviously better than the latter. The linear expansion coefficient and thermal conductivity of the alloy were measured. The properties of 304B7 high boron steel are similar to those of 304 stainless steel. 2022 Vol. 32 (05): 52-55 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 56 Influence of SrO on sintering properties of magnesia-alumina spinel Hot! ZENG Haiyan，ZHANG Wangnian，FANG Yan，DENG Shujiao DOI: 10.13228/j.boyuan.issn1006-6543.20210052 Magnesia alumina spinel was prepared from Al2O3, Mg(OH)2 and SrO, with mass fractions of SrO is 0, 0.25%, 0.5%, 0.75% and 1%, respectively. The sintered samples were analyzed by X-ray diffractometer, scan‐ ning electron microscope, apparent porosity and bulk density tester and image processing software. The results show that after calcination at different sintering temperatures, with the increase of SrO content, the linear shrink‐ age and bulk density of the samples increase first and then decrease, and the apparent porosity decreases first and then increases. When the addition of SrO is 0.5%, the linear change rate and bulk density are the largest and the apparent porosity is the smallest. When the sample is sintered at 1 600 ℃ for 3 h, the linear change rate of mag‐ nesium aluminum spinel prepared without SrO after sintering is 4.9%, the apparent porosity is 50.1%, and the bulk density is 1.64 g/cm3; The linear change rate of magnesia alumina spinel prepared by adding 0.5% SrO is 5.4%, the apparent porosity is 44.3%, and the bulk density is 1.89 g/cm3. 2022 Vol. 32 (05): 56-60 [Abstract] ( 5 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 61 Study on microstructure and properties of Cr2AlC/Ni5Al composite coating Hot! Zhang Weiping，Zhang Penglin，Niu Xianming DOI: 10.13228/j.boyuan.issn1006-6543.20210123 Pure Cr 2AlC (MAX phase) powder was prepared by pressureless sintering, and then used as the rein‐ forcing phase of Ni5Al powder material. Atmospheric plasma spraying (APS) was used to prepare Cr2AlC/Ni5Al self-lubricating composite coatings with different Cr2AlC content. The microstructure and properties of the coat‐ ings were analyzed, and the friction properties of the composite coatings were focused on. The results show that the coating is dense as a whole, and the components exhibit good wettability. Cr2AlC significantly improves the hardness of the composite coating. The 10%Cr2AlC-Ni5Al composite coating has the lowest friction coefficient and wear rate, 0.45 and 1.82×10-5 mm3/(N·m) respectively. The surface cracks of the coating are significantly re‐ duced, and the self-healing properties of Al2O3 protect the coating. As the content of Cr2AlC increases, the porosi‐ ty of the coating increases and the tribological properties of the composite coating decrease. 2022 Vol. 32 (05): 61-67 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 68 Microstructure and wear resistance in laser cladding of NiAl based alloy Hot! QU Yuebo，LIU Zhenbo，HAN Wei，ZHAO Lin，LI Changhai，TIAN Zhiling DOI: 10.13228/j.boyuan.issn1006-6543.20220100 Laser cladding was carried out to prepare Ni3Al based alloy coatings on 45 steel by using Ni3Al/ 25%Cr 3C2 mixed powder. Microstructure and wear resistance of the cladding materials was investigated. The results indicate that the microstructure of the Ni 3Al based cladding materials contains mainly Ni3Al, NiAl, and in situ-formed Cr 7C3. The hardness of the cladding materials is 599.6HV0.1, about 2.73 times of that of 45 steel. Ni 3Al based cladding materials show sound wear resistance, owing to homogeneous distribution of fine Cr7C3. The wear mechanism of the cladding materials is abrasive wear, and its friction coefficient is about 0.55. The spe‐ cific wear rate of the cladding materials is 1.12×10-5 mm3/N·m, only 28.6% of that of the vermicular graphite cast iron. 2022 Vol. 32 (05): 68-73 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 74 Al-Cr composite coating laser cladding on 7075 aluminum alloy Hot! ZENG Xiaoping，WANG Qiulin，MA Yaxin，ZHANG Hong DOI: 10.13228/j.boyuan.issn1006-6543.20210088 In order to strengthen the surface of 7075 aluminum alloy, an Al-Cr composite coating was prepared by laser cladding technology. Scanning electron microscope (SEM) and optical metallurgical microscope (OM) were used to observe the structure of the composite coating. Energy dispersive spectrometer (EDS) was used to elemental analysis, X-ray diffraction (XRD) was used to phase analysis, and the micro-hardness of the composite coating was tested. The results show that the Al-Cr composite coating prepared by laser cladding technology is relatively smooth, without obvious cracks, and forms a good metallurgical bond with the substrate. The compos‐ ite coating consists of a metal phase (Al and a small amount of Cr) and a ceramic phase (AlxCry intermetallic compounds). There are two reactions mechanisms of Cr and Al in the coating: liquid-solid reaction and solid-sol‐ id reaction. The Al phase of the metal plays the roles to bond the coating to the substrate，increase the toughness of the coating and reduce the generation of cracks. The coating experiences different laser passes, so there are dif‐ ferences in the structure and phase composition of each part, which leads to changes in performance. The microhardness of the coating is gradually distributed along the depth of the molten pool and gradually decreases. The surface hardness is maximum 977.4HV 0.5, which is a 6.88 times increase compared to 7075 in the T6 state. 2022 Vol. 32 (05): 74-79 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 80 The friction and wear properties of WC/Al2O3 composite cermet coating sprayed on AZ91D magnesium alloy Hot! ZHOU Junhui，HUANG Cong DOI: 10.13228/j.boyuan.issn1006-6543.20220056 WC/Al 2O3 composite cermet coating was sprayed on AZ91D magnesium alloy by supersonic plasma spraying technology.The surface structure, coating thickness and the bonding strength between coating and matrix were tested by X-ray diffraction (XRD) , scanning electron microscope (SEM ), thickness gauge, viscometer and other equipments.And the friction and wear properties of the coating were measured by the coating wear tester. The results show that the bonding strength is about 35 MPa when the coating thickness is controlled at 0.8~ 1.0 mm.The principal crystalline phases of the coating are WC and Al2O3 phases and the spraying effect of com‐ posite cermet coating is good.The photo of SEM shows that the coating has stable layer structure and lower po‐ rosity. The coating could obtain excellent wear resistance(rate of wear is 13.9×10-3 mm3/(N·m) when the coating temperature is 400 ℃. The coating friction factor is stable at 0.272, the wear amount is 0.003 5 g, and the wear mechanism is abrasive wear when the test load of the friction and wear test is 5 N and the time is 2 h. 2022 Vol. 32 (05): 80-84 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 85 Effect of polymer modified anodes on electrochemical properties and cobalt leaching of PEMFC Hot! GUO Xibin，WANG Qiao，CHENG Xiaoqi DOI: 10.13228/j.boyuan.issn1006-6543.20200152 The electrochemical polymerization reaction between aniline and thiophene monomer was carried out on the electrochemical workstation, and which was deposited on the surface of carbon paper, and the polymer modi‐ fied anode was prepared. The anode was used for extraction and recovery of lithium cobalt oxide in PEMFC, and the factors effect the electric capacity of PEMFC were analyzed, and the leaching state of lithium cobalt oxide cath‐ ode was tested. The results show that the modified PTh carbon paper forms a folded surface after electrodeposition, and the specific surface area increases rapidly. PTh modified carbon paper has been prepared by electrochemical polymerization, and a CV curve with a larger area has been formed after modification. The anode is obtained a larg‐ er specific surface area by using the electrochemical polymerization, which significantly improves the electrical performance of unit and shows a higher chemical stability and electric storage capacity than the polyaniline. The PTh modified carbon paper reaches the largest Co2+ growth rate when the operation cycle is 245 h, which is more likely to achieve the effect of Co (Ⅲ) leaching, and acquires a strong production capacity. 2022 Vol. 32 (05): 85-89 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 90 Effect of pressing pressure on microwave sintering structure of Cu60Cr40 Alloy Hot! WANG Yang，DONG Zhongqi，LI Tianyu，ZHANG Baoyu，LIU Hao DOI: 10.13228/j.boyuan.issn1006-6543.20200165 Cu 60Cr40 alloy was prepared by mechanical alloying and cold pressing microwave sintering. The density and phase composition of the alloy were measured. and the microstructure evolution of Cu60Cr40 alloy under differ‐ ent pressing pressures was studied. The results show that the microstructure of Cu60Cr40 alloy powder and cold pressing greenbody is lamellar. With the increase of pressing pressure, the green density of Cu60Cr40 alloy gradually increases. Under cold state, the density gradually increases from loose to dense, and the formability improves. After microwave sintering, the microstructure of Cu60Cr40 alloy is lamellar. With the increase of pressing pressure, the grain boundary becomes obvious gradually, the void decreases, and the density increases. 2022 Vol. 32 (05): 90-95 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 96 Research status of powder extrusion 3D printing Hot! HU Jianbin，LIU Xiaojing，YANG Jianming，SHANG Feng，HE Yiqiang DOI: 10.13228/j.boyuan.issn1006-6543.20210119 Powder extrusion 3D printing, combined the idea of powder injection molding (PIM) and 3D printing, is a new 3D printing technology emerged in recent years, which can be used to fabricate metal, ceramic or com‐ posite parts and avoid the disadvantages of PIM and some previous main 3D printing method. The principle of powder extrusion 3D printing is introduced by contrasting this method to PIM. The features of powder extrusion 3D printing are also summarized compared to PIM and some other 3D printing method. The feedstock of pow‐ der extrusion 3D printing used in the previous main researches, the structure composition of the printer and extru‐ sion ways of the feedstock are present. The development and research situation of the feedstock and printer, and their effect on products are described. The future research directions aiming at the existing problems of powder extrusion 3D printing are proposed. 2022 Vol. 32 (05): 96-102 [Abstract] ( 5 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 103 Progress in simulation on atomization process of powder preparation Hot! HU Jiaqi，CHENG Zonghui，BAI Bing DOI: 10.13228/j.boyuan.issn1006-6543.20210142 Spherical metallic powder plays a key role as crucial industrial raw materials. which has been univer‐ sally applied into multiple manufacturing fields, such as additive manufacturing, thermal isostatic pressure, me‐ tallic injection molding, spraying, etc. Current preparation processes for metallic powders primarily consist of normal atomization, electrode induced gas atomization, plasma rotating electrode process and plasma atomiza‐ tion. The preparation processes for metallic powders include a series of complicated physical-chemical processes. To gain a profound insight into the complex preparation processes and further optimize the processing pa‐ rameters as well as apparatus, the research focused on the simulation of preparation processes for powders is systematically reviewed in the current work. And the future development of atomization process simulation for metallic powders is also prospected to provide a convincing theoretical evidence for production practice. 2022 Vol. 32 (05): 103-109 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 110 Research progress and application of preparation technology of porous metal materials Hot! ZHAO Lijie，ZHANG Fang，PENG Jun，MING Shoulu，ZHU Ruizong DOI: 10.13228/j.boyuan.issn1006-6543.20210128 As a new type of lightweight metal, porous metal is a kind of metal materials with both structure and functionality, which has many advantages the traditional metals do not possess, such as small specific gravity, large specific surface area, and strong heat dissipation ability. It is a new type of functional material research hot spot. The preparation methods and the principles of porous metal materials, including sintering method, casting method and other methods are briefly described, porous metal materials used in the fields of filtration and separation, sound insulation and noise reduction, catalyst carriers, and medical biological materials are introduced. Develop‐ ment status and wide application of a new technology for obtaining porous stainless steel by high temperature vacu‐ um reduction sintering in the form of powder metallurgy with iron oxide scale produced in the rolling process as the main raw material is proposed. This technology integrates the reduction of iron oxide scale and the sintering of metal particles into one step, the preparation process is simplified to a certain extent, the preparation time is short‐ ened, and the production efficiency is improved. Finally, the future development trend of porous metal materials in the future is prospected. 2022 Vol. 32 (05): 110-116 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 117 Research progress on high-value utilization of copper slag Hot! TANG Chaofan，ZHANG Rongliang DOI: 10.13228/j.boyuan.issn1006-6543.20210129 Copper slag is a solid waste produced by smelting copper, which is called a "secondary mineral" be‐ cause it is rich in valuable metal components. The accumulated copper slag has brought a huge burden to the en‐ vironment and ecology, encroaching on land resources, polluting the water environment and the atmosphere. In order to find an efficient treatment method for copper slag, the latest research results on the comprehensive utili‐ zation of copper slag are reviewed, and the advantages and disadvantages of physical utilization, fire, wet, com‐ bined, and biological treatment of copper slag are analyzed, to provide research direction to realize the resource utilization of copper slag. 2022 Vol. 32 (05): 117-123 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 124 The Research and development of titanium dioxide production technology Hot! ZHANG Hongying，WANG Guanghui DOI: 10.13228/j.boyuan.issn1006-6543.20200224 Titanium dioxide commonly known as titanium white is the third largest inorganic chemical product after synthetic ammonia and phosphorus chemical industry. China is the world's largest producer and consumer of titanium dioxide. The sulfuric acid process, chlorination process and hydrochloric acid process of the titanium diox‐ ide production are reviewed, and the advantages and disadvantages of each process are analyzed in detail. China is vigorously developing the clean production process of titanium dioxide. We should strive to improve the technol‐ ogy level of the sulfuric acid process, and eliminate the backward production facilities. At the same time, adjust‐ ment and layout of the chlorination process should been emphasized. The development of new processes and tech‐ nologies for the production of high-quality titanium dioxide are also important to realize the sustainable develop‐ ment of titanium dioxide industry in China. 2022 Vol. 32 (05): 124-129 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 130 Research progress in electrochemical detection of disease markers using nanomaterials Hot! GUO Xiaohui，FAN Yingwei DOI: 10.13228/j.boyuan.issn1006-6543.20200292 Disease markers are a kind of indicators that can objectively reflect normal physiological conditions and disease development, and play a key role in clinical medical diagnosis. Electrochemical biosensors have re‐ ceived wide attention from researchers in recent years for their unique analysis and detection methods and their potential applications in clinical medicine. The detection of disease markers by electrochemical biosensors based on graphene, precious metal nanoparticles, carbon nanotubes, quantum dot materials, and nano-oxide materials are described, and finally the detection of disease markers by electrochemical biosensors, the research direction and future development trend are prospected. 2022 Vol. 32 (05): 130-135 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 136 The influences of different segment ratios on drilling performance of thin-wall diamond bits Hot! CAO Caiting，LIU Yibo，XU Yanjun，HE Wenkai，PEI Youdong DOI: 10.13228/j.boyuan.issn1006-6543.20210120 Thin-wall diamond bits suitable for 2.0~3.5 kW drilling rigs and processing reinforced concrete were selected to study the influences of different segment ratios on drilling performance. Based on the preliminary tests, FS type, 24 mm×3.5 mm×11.5 mm, diamond array patterns segments were selected to weld on the steel ma‐ trix of diameter 63, 83, 102, 152 and 200 mm. Each specification bit welded three different segment ratios. The cutting performance on C45 reinforced concrete was tested under wet drilling condition. The results show that when the segment ratio of diameter 63 bit is 72.79%, the segment ratio of diameter 83 bit is 73.67%, the segment ratio of diameter 102 bit is 74.93%, the segment ratio of diameter 152 bit is 70.39%, and the segment ratio of diameter 200 bit is 68.78% separately, the cutting speed is the fastest with hand of operator feels stable. Based on the fact that customers give priority to cutting speed than the cutting feeling, when using thin-wall diamond bits, it can be concluded that the comprehensive performance is optimal when the segment ratio is about 70%. 2022 Vol. 32 (05): 136-150 [Abstract] ( 6 ) HTML (1 KB)  PDF  (0 KB)  ( 2 )

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