Xiaoliang SHI
,
Gangqin SHAO
,
Xinglong DUAN
,
Runzhang YUAN
,
null
,
null
,
null
材料科学技术（英文）
Nanocrystalline tungsten carbide-cobalt (WC-Co) composite powders produced through spray thermal decomposition-continuous reduction and carburization technology were used to prepare Φ3.25 mm×38 mm ultrafine tungsten carbide-cobalt (WC-Co) cemented carbide rods through vacuum sintering plus sinterhip technology. The microstructure, Vickers hardness, density and Rockwell A hardness (HRA), transverse rupture strength (TRS), saturated magnetization and coercivity force were tested. The results show that the average grain size of the sintering body prepared through vacuum sintering plus sinterhip technology was 430~nm; transverse rupture strength (TRS) was 3850 MPa; Vickers hardness was 1890 and Rockwell A hardness of sintering body was 93. High strength and high hardness ultrafine WC-Co cemented carbide rods used to manufacture printed circuit board (PCB) drills were obtained.
关键词:
Nanocrystalline
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null
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null
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null
Yongshen HU
,
Wen CHEN
,
Qing XU
,
Runzhang YUAN
材料科学技术（英文）
(PEO)(x)MoO3.nH(2)O(x=0 similar to2) nanocomposite films were prepared by ion exchange method and polymer solution direct intercalation in sol-gel route. The synthesis and structure of the films were investigated by XRD, DSC, FTIR, etc. The results show that MoO3 xerogel has a layered structure, which arranges in b-direction. The interlayer distance Of MoO3 xerogel increases from 0.690 nm at x=0 to 1.308 nm at x=2 after heat treatment. PEO can be completely intercalated into the interlayer at x=0.5 similar to1 and has strong interaction with MoO3 host.
关键词:
Huaping XIONG
,
Lianmeng ZHANG
,
Junguo LI
,
Runzhang YUAN
材料科学技术（英文）
The tungsten heavy alloys with Ni-Al and Fe-Al additives were sintered by hot-press method at 1473 K for 1 h. It was found that the relative density of the W-Fe alloy could be increased evidently by addition of Al. However, the relative density of W-Ni-Al alloy with low content of Al was conversely decreased considerably compared with that of W-Ni alloy. The causes have been studied. The sintering experiments of Mo alloy and W-Mo alloys with 3 wt pct Fe-1.5 wt pct Al additives were also carried out under the same sintering condition of low temperature. Finally, W-Mo system FGM with density gradient was successfully fabricated. Its density changed gradually from 17.0´103 kg/m3 to 9.5´103 kg/m3 within the middle 1.1 mm thickness range.
关键词:
Rongzhou GONG
,
Zekun FENG
,
Jianguo GUAN
,
Runzhang YUAN
材料科学技术（英文）
A novel magnetorheological (MR) suspension was based on methyl silicone oil and cobalt-phthalocyanine (Co-Pc)/Fe nanocomposite particles, which were synthesized by thermally decomposing liquid carbonyl Fe in the solution of Co-Pc in N, N-dimethyl formamide. The nanocomposite particles were fully characterized by XRD, SEM and HREM, and the thermal, magnetic and MR properties of nanocomposite particles were measured. Such factors as weight percent of particles (w), magnetic field strength (H), temperature (T) and shear rate (gamma) etc influencing on MR properties were investigated. The results indicated that Co-Pc/Fe nanocomposite with density of 3.66 g/cm(3) was almost micro-sized regular spheroids consisting of tens of Co-Pc coated alpha -Fe nanoparticles in inner and Co-Pc layers on surface of the spheroids. They showed good characteristics of anti-oxidation and soft magnetic. Increment of w increased field-induced shear stress (Delta tau) and zero-field viscosity (eta (0)) of MR suspensions monotonously, and improved anti-settlement stability, but eta (0) increased more markedly than Delta tau with increasing w. Delta tau was basically independent on T and gamma while increased obviously with increasing H. With increasing T, response time of the MR suspension to external magnetic field seemed to decrease. As a result, MR suspensions with satisfactory stability and rapid, completely reversible and significant MR effect can be obtained from Co-Pc/Fe nanocomposite particles.
关键词:
Hong TAO
,
Chengji DENG
,
Lianmeng ZHANG
,
Runzhang YUAN
材料科学技术（英文）
Al/Al2O3 composites of different ratios were hot-press sintered at 575 similar to 640℃ under a pressure of 30 MPa for 2 h in a vacuum furnace. It was found that the relative density of the Al/Al2O3 composites could be increased evidently with the rise of sinter temperature. No reaction occurred between Al and Al2O3 at the sinter temperatures. Under 640℃-30 MPa-2 h experimental condition, Al/Al2O3 system FGM was successfully fabricated, and its density range changed quasi-continuously from 2.887x10(3) kg/m(3) to 3.1909x10(3) kg/m3 within the middle 1.0 mm thickness range.
关键词:
Qing XU
,
Wen CHEN
,
Duanping HUANG
,
Runzhang YUAN
材料科学技术（英文）
Doped SrTiO3 capacitor-varistor multifunctional ceramics were fabricated by a single sintering process. AC complex impedance analysis was performed to investigate electrical features of grains and grain boundaries for both as-reduced ceramic and reoxidized ceramics.The results showed that the as-reduced ceramic exhibited inductive response at high frequencies above 2 MHz, which is attributed to the contribution of electron behavior in semiconducting grains.The high frequency inductive response disappeared in impedance plots of reoxidized ceramics.
关键词:
Strontium titanate
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null
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null
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null
Transactions of Nonferrous Metals Society of China
A new process for the hydrometallurgy of refractory gold concentrates was presented. The process comprises grinding-leaching, intensified alkaline leaching (IAL), cyanidation and adsorption. In a stirring-type pulverizing-leaching tower mill, the concentrate is ground to <35. 6 μm of 95. 5 % while simultaneously leached by NaOH of 12 kg/t, then carried out intensified alkaline leaching for 48 h by NaOH of 108 kg/t in enhanced agitation tanks with the pulp concentration of 40% solids at the environmental temperature of 9. 5 &SIM; 13. 5 &DEG;C and the environmental pressure of 10(5) Pa. The oxidation rate of As is 94. 9%, and 47. 6% for S. The total consumption of NaOH is only 20% of that theoretically calculated under the conditions of full oxidation at the same oxidation rates of arsenic to arsenate and sulfur to sulfate. The gold leaching rate by NaCN in 24 h is increased from 9. 2% before pretreatment to 94. 2%. The consumption of NaCN is 7. 5 kg/t, which is one times less than that before pretreatment. The extraction cost of gold is about 422 Yuan/t.
关键词:
refractory gold concentrates;grinding-leaching;intensified alkaline;leaching (IAL);pretreatment;common temperature and pressure
