Gas evolution from powders of the copper selenide Cu1.985 Se

Conclusions At low temperatures water predominates in the compositions of desorbed gases. As the temperature is raised, CO₂, CO, O₂, CH₄, and H₂ begin to be liberated, their amount increasing with rising temperature, while the amount of H₂O decreases. Prolonged (30-h) vacuum annealing at 523–573°K enables a specimen of the material to be almost completely degassed. A degassed specimen exhibits increased sorptive power, especially with respect to water.Translated from Poroshkovaya Metallurgiya, No. 7(259), pp. 25–29, July, 1984.     

Mössbauer spectroscopy of iron phosphide powders

Conclusions The Mössbauer spectra of iron phosphides at 65°K were recorded for the first time. It was established that in the Fe₃P, FeP, and FeP₂ crystal structures, the crystallographically equivalent positions of iron are not equivalent with respect to the magnitude of effective magnetic field or of electric field gradient on the nucleus. Mössbauer spectra enable phase analysis to be carried out on iron phosphide powders.Translated from Poroshkovaya Metallurgiya, No. 1(229), pp. 57–61, January, 1982.     

喷雾干燥-氢还原制备超细/纳米晶W-10Cu粉末及其烧结行为

采用喷雾干燥-氢还原法制备超细/纳米晶W-10Cu(质量分数,%)复合粉末,并经过压制和烧结制备W-Cu复合材料,系统研究烧结温度和保温时间对该材料性能和组织的影响,以及在1 100～1 300℃温度范围内的烧结激活能。结果表明,W-10Cu还原粉末晶粒度仅为30～60 nm;在1 200℃烧结时开始发生明显的致密化行为;随烧结温度升高相对密度增大,当烧结温度升高到1 300℃时W-10Cu复合材料的相对密度为90%,但当温度达到1 460℃时有所降低。1 420℃保温90 min时材料相对密度高达99.1%,且此时晶粒度仅为1.8μm。W晶粒尺寸为30～60 nm的W-10Cu复合粉末在1 100～1 300℃烧结的平均激活能为129.14 kJ/mol。烧结温度为1 420℃时W-10Cu的电导率随保温时间延长先增大后减小,保温90 min时最大达到19 MS/m,超过国标有关规定。     

Preparation and characterization of perovskite REFeO3 nanocrystalline powders

Combustion of nitrate-citrate gel was employed to prepare REFeO3(RE=Y,La and Gd) nanocrystalline powders.The samples were characterized with X-ray diffraction(XRD) analysis,thermal analysis(TG/DTA) and transmission electron microscopy(TEM).LaFeO3 crystallites were directly obtained by the sol-gel combustion process,and orthorhombic YFeO3 and GdFeO3 were formed when annealed at 800 oC.The investigation of magnetic properties showed that YFeO3 and LaFeO3 exhibited ferromagnetic behavior,while GdFeO3 presented...     

Preparation of the mixtures of ultrafine powders of nickel,cobalt, and copper

Translated from Poroshkovaya Metallurgiya, No. 7(355), pp. 5–9, July, 1992.     

Effect of Cu3P addition on sintering behaviour of elemental powders in the composition of 465 stainless steel

Abstract

The addition of Cu₃P for developing the high strength 465 maraging stainless steel from elemental powders was studied. The sintering parameters investigated were sintering temperature, sintering time and wt-%Cu₃P. In vacuum sintering, effective sintering took place between 1300 and 1350°C. The maximum sintered density of 7·44 g cm^?3 was achieved at 1350°C for 60 min with 4–6 wt-%Cu₃P. More than 6 wt-%Cu₃P content and temperature >1350°C caused slumping of the specimens. The sintered specimens were heat treated and a maximum ultimate tensile strength (UTS) of 767 MPa was achieved with 4 wt-%Cu₃P content. The maximum hardness of 45·5 HRC was achieved in heat treated condition with 4 wt-%Cu₃P content. Above 4 wt-%Cu₃P content increase in density was observed whereas the response to heat treatment decreased. Fracture morphologies of the sintered specimens were also reported. A comparison of sintering behaviour and mechanical properties of elemental powders with prealloyed powders was also given in the present study.     

Increase in the formability of powders that are difficult to deform

The flowing capacity and relative poured density (RPD) of different fractions of original gas-sprayed high-speed steel powders and those treated in rolls as well as the strength of compacts prepared from them are studied. It is established that with this treatment powder particles are mainly broken down, and their flowability and RPD decrease. The ultimate RPD for treated powders with which quite strong compacts are obtained under normal cold pressing conditions is about 0.45.Compacts with satisfactory processing characteristics are obtained from powders with a RPD below 0.45. A relative poured density of 0.45 may serve as a production criterion of the suitability of powders that are difficult to deform for normal compaction.     

Electroless tinning of copper powders

Conclusions A study was made of the tinning of copper powders from solutions. Under optimum conditions (duration 10–15 min, temperature 40°C) the process enables a tinned copper powder to be obtained of any desired tin content.Translated from Poroshkovaya Metallurgiya, No. 2(194), pp. 1–3, February, 1979.     

Behavior in vacuum at high temperatures and thermodynamic properties of nickel phosphide Ni3P

Translated from Poroshkovskaya Metallurgiya, No. 12 (360), pp. 70–72, December, 1992.     

还原铜粉之注射成形

平均粒度约10μm的微细还原铜粉因不规则粉末形态及残留有较高的氧含量，而不易以注射成形工艺来制备高性能产品。本研究发现，采用具较多量之主干高分子为基础的多元粘结剂能克服不规则粉末形态所导致之严重粉末间之磨擦，而将这种微细还原铜粉顺利的注射成形。烧结时，若能在烧结孔洞封闭之前将粉末中的残留氧化物有效的予以还原，如在低于900℃之温度下给予适当保温，则注射成形组件之烧结密度可高达95％理论密度。在此条件下，注射成形组件的导电率可达纯铜导电率的80％以上。     

Injection moulding of oxide reduced copper powders

Abstract

Fine oxide reduced copper powders of about 10 μm mean grain size are irregular in particle shape and high in oxygen content, which poses a difficulty in achieving good properties from injection moulding. Injection moulding was possible when a multicomponent binder with a large fraction of the backbone polymer was used. Injection moulded parts could be sintered to a density of about 95% theoretical, if reduction of the residual oxides in the powder was effectively carried out prior to closure of pores during sintering. Under such a condition, the injection moulded parts could attain an electrical conductivity higher than 80% of pure copper. July 2004.     

低氧铜杆线铜粉剥离原因分析及其对策措施

表面铜粉剥离,导致铜杆线表面损伤,其对铜杆线拉伸过程具有较大影响。通过扫描电镜分析,剥离铜粉厚度可达25μm,经物相分析确定其主要成分为铜及铜的氧化物。通过对剥离物和杆线表面缺陷进行形貌分析,以铜杆线的生产、加工各环节作为研究对象,并确认了铜杆轧制工艺、无酸清洗工艺、线表擦伤、拉伸角度及拉丝模具等5方面影响因素,制定了相应的对策措施。研究表明,铜杆氧化物剥落和机械损伤是铜粉剥离的主要原因,在铜杆线生产、加工环节,防止氧化物带入铜基体和避免铜线表面损伤能有效减少铜杆线铜粉剥离。