Change in Iron Powder Properties with Treatment in Rolls

Conditioned iron powders are prepared by carbothermal reduction of “Blue Dust” (India) ore concentrate followed by compaction treatment in rolling mill and a decarburizing anneal. The properties of powder prepared by grinding in a vibration and rolling mill are determined. The method makes it possible to control the bulk density of the powder from 1.75 to 2.75 g/cm³. Determination of the production properties of the powders obtained and powder NC.100.24 by the same procedure established satisfactory conformity of the results. The technological desirability of preparing conditioned iron powder by treatment in a rolling mill is demonstrated.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 12–16, March–April, 2005.     

Mechanical and hydraulic characteristics of P/M titanium filters

Conclusions For the production, by hydrostatic pressing, of filters from PTÉK, PTÉS, and PTÉM electrolytic titanium powders and a screened 0.63–1.0 mm fraction of the powder forming during the crushing of TG-Tv titanium sponge, the recommended pressure range is 78.5–157 MPa. The mechanical strength of filters from screened TG-Tv powders is, other things being equal, 1.2–4 times higher than that of filters from electrolytic powders. The filtration indicators (coefficients of permeability and filtration) of filters from screened TG-Tv and electrolytic powders are generally virtually identical, but with coarse (0.63–1.0 mm) electrolytic powders they are two to seven times higher than with electrolytic powders.Translated from Poroskhovaya Metallurgiya, No. 7(235), pp. 34–39, July, 1982.     

Powder Metallurgy Overcomes Economic Difficulties

The state of the production of metallic and ceramic powders (including nano-dimensional powders) and of articles fabricated from these powders in North America is discussed. New technologies that produce an increase in the density and improvement in the mechanical properties of powder-based articles are considered. Technological developments and articles for which prizes were awarded by the North American Metal Powders Industry Federation in 2003 are adduced.__________Translated from Poroshkaya Metallurgiya, Nos. 1–2(441), pp. 117–125, January–February, 2005.     

Effects of raw material on the properties of partially alloyed powders and low-carbon materials based on them

Studies have been made on the effects of the raw material (cast iron and steel powders) on the properties of partially alloyed powders of grades D2, D2M, N2M, N2D2M, and N4D2M and also of materials based on them made by single pressing and sintering. When iron-bearing semifinished products are used, or the cast iron and steel powders, one can make partially alloyed powders with various compositions having good technological characteristics as well as materials based on them having good physical and technological properties.Institute of Problems of Materials Science, National Academy of Sciences of the Ukraine, Kiev. Translated from Poroshkovaya Metallurgiya, No. 7–8, pp. 67–72, July–August, 1994.     

Development of a technology for pressing high-density products using gas-draining methods

The factors that hinder the formation of high-density compacts by cold-pressing of powders are considered. The main factors are the gases present in the charge and the technological lubricant introduced to facilitate the work of the press mold. A procedure has been developed for calculating the efficiency of gas drainage from a mold and the pressure in gas pores in the compacts. Recommendations are made for increasing the density of compacts from iron powders by a single cold pressing.Scientific-Industrial FirmBakkonditsioner,Baku. Translated from Poroshkovaya Metallurgiya, No. 5–6, pp. 34–39, May–June, 1994.     

Energy and force conditions of hydrostatic pressing of blanks from powder materials

Conclusions An examination is made of the hydrostatic pressing of metal powders. The total work done in this process is made up of six components. Their determination and methods of calculating them are described. Equations are proposed for calculating the work done in overcoming friction in the gland of the hydrostatic pressure vessel plunger. The equations allow for the variation of the coefficient of friction in the gland, which is a function of pressure in the vessel. Energy expenditure in hydrostatic pressing determined by calculation is in accord with experimental data. This shows that the equations proposed can be employed for choosing plant in the development of new technological processes for the production of parts from metal powders by hydrostatic pressing.Translated from Poroshkovaya Metallurgiya, No. 6(222), pp. 32–36, June, 1981.     

Laser synthesis of ultradisperse powders of aluminum oxide

We have studied laser synthesis and the structure and properties of ultradisperse aluminum oxide powders. We show that the laser radiation intensity affects the phase composition. We find that the following conditions are optimal for production of these powders: power 500 W, pressure 0.1 atm (1–10 kPa), helium as the synthesis atmosphere.Scientific-Research Institute of Problems in Powder Technology and Coatings, Republic Engineering and Technical Center of Powder Metallurgy, Perm. Translated from Poroshkovaya Metallurgiya, Nos. 1/2(377), pp. 1–4, January–February 1995.     

Standardization of powders of high-alloy steels and alloys

Conclusions The current state of researches into the production of powders of high-alloy steels and alloys is examined. The new GOST standard for such powders is reviewed.Translated from Poroshkovaya Metallurgiya, No. 5(65), pp. 6–10, May, 1968.     

Theory,preparation technology,and properties of powders and fibers effect of heat treatment on the properties,structure, and magnetic properties of iron-nickel alloys with micron particle size

A method is suggested for producing very fine iron-nickel alloy powder by electrolysis in a two-layer electrolytic bath using a hydrocarbon solvent from an oil refining fraction as an upper organic layer with evaporation at 180°C and subsequent reduction annealing in a hydrogen atmosphere. The reduction annealing temperature has been studied for its effect on composition, structure, and magnetic properties of micron size powders. Results of studying the phase and chemical composition of powders and their particle shape are provided. These studies make it possible establish the optimum heat treatment conditions in the production of very fine iron-nickel alloy powders whose chemical composition is similar to those produced by the carbonyl method.Institute of Colloid Chemistry and Water Chemistry, Ukrainian National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 3/4, pp. 1–5, March–April, 1995.     

Study of the Process of Phase Formation during Detonation Spraying of Composite Powders of the FeTi - SiC System

We have studied the dependences of the structure, phase composition, and properties of coatings obtained by detonation spraying of powders of the system 77 mass% FeTi - 23 mass% SiC on the method by which they are prepared. We have established substantial differences in morphology and composition for coatings sprayed from conglomerated and presintered powders. We have shown that the process of formation of new phases occurs more rapidly when spraying conglomerated powders.__________Translated from Poroshkovaya Metallurgiya, Nos. 1–2(441), pp. 67–73, January–February, 2005.     

Some properties of components from iron powder alloyed with 6% chromium

Summary The process developed at the Institute for thermal diffusion impregnation from point sources is simple and reliable, and permits production of iron-chromium alloy powders of any desired composition. Compared with parts of pure iron, constructional components obtained from these powders exhibit higher strength, ductility, and oxidation resistance.Translated from Poroshkovaya Metallurgiya, No. 8(56), pp. 28–33, August, 1967.     

Clssified refractory compound powders

Conclusions Technical quality requirements for refractory compound abrasive powders and optimum conditions for the comminution and classification of some refractory compound powders have been determined. A study was made of some physicomechanical properties (strength, abrasive ability, specific surface, and apparent density) of TiB₂, TiC, and TiN powders. The existence of a method for the manufacture of refractory compound abrasive powders and data yielded by a study of their physicomechanical characteristics will enable these powders to be used in the near future on a wider scale in tool production.Translated from Poroshkoyaya Metallurgfya, No. 6(234), pp. 92–98, June, 1982.     

Production of metal powders from melts by centrifugal atomization

Conclusions A study was made of centrifugal atomization of molten metals in argon at low argon consumption rates [(5.2–7.5) · 10^–3 NTP m³/kg]. Output with a single injector attained 30–40 kg/h. Increasing the molten metal head to 0.6–0.8 MPa and decreasing the nozzle diameter to 0.3 mm substantially increased the fineness of the powders. Raising the head still further influenced the effectiveness of atomization to a smaller extent, and decreasing the nozzle diameter to less than 0.3 mm coarsened the powders. Powders of magnesium, aluminum, and Br020 alloy. (20% Sn-Cu bronze) produced by centrifugal atomization of superheated (by about 30–50°K) melts in an inert atmosphere (argon) had spherical particle shapes, which imparted to them good flowability. The oxygen content of the powders was low (less than 0.08%).Translated from Poroshkovaya Metallurgiya, No. 12(276), pp. 5–10, December, 1985.     

Sintering of molybdenum pressing in moist hydrogen and their rolling into strip

Conclusions A method has been developed and introduced into production for the preparation of molybdenum powders and the sintering of plates from them suitable for rolling without the use of high-temperature welding in a welding apparatus. The method has been used to produce molybdenum sheets in squares from 100×100 to 180×180 and thickness from 1 to 3 mm in amounts of 5–6 t per year.     

Production of fine tin powders of various degrees of purity

Conclusions Pneumoacoustic atomization enables the yield of fine tin powder fractions to be increased by 20–30% compared with the pneumatic method. The purity of resultant powders is higher than that of powders comminuted mechanically in the presence of a SAA.Translated from Poroshkovaya Metallurgiya, No. 5(281), pp. 7–9, May, 1986.     

Control over the particle size of stainless-steel powders

Conclusions Replacing some of the metallic iron by ferric oxide, Fe₂O₃, in the charge for the preparation of Kh18N15 and Kh23N28 stainless-steel powders by the calcium-hydride reduction process increases (two- to threefold) the yield of the fine fraction (-0.063 mm) without affecting the apparent density of the powders (1.4–1.85 g/cm³) or the sponge shape of their particles. At the present time, stainless-steel powders are being manufactured using a charge in which 20–30% of metallic iron has been replaced by the oxide Fe₂O₃.Translated from Poroshkovaya Metallurgiya, No. 2 (134), pp. 1–8, February, 1974.     

Strength of porous sintered sheet materials

Conclusions The strength of porous sintered sheet materials can be evaluated by the formaulas of Bal'shin, Ryshkevich, and Shcherban'. We determined the values of the constants in these formulas for sheets of powdered strainless steel of joint reduction, calcium hydride titanium, nickel, and Nichrome.In technological tests the largest number of reversed bendings is sustained by porous sheets rolled from powders of fine fractions. Differences in the plasticity of porous sheets from powdered stainless steel and Nichrome manifest themselves with bending radii of 2 and 5 mm.Translated from Poroshkovaya Metallurgiya, No. 2(302), pp. 92–96, February, 1988.     

Interphase reactions in forming plasma coatings

Nickel-plated powders and coatings of titanium and chromium carbides and borides are studied. Components of the starting powders react between themselves and with oxygen from the atmosphere forming solid solutions, intermetallic compounds, and a shielding oxide film. During pulverization the surface of particles does not lose a plated layer and nickel metal is always available in the coating. In order to increase the life of coatings it is advisable to use powders with the minimum possible amount of oxygen which promotes decomposition of higher carbide. In order to reduce the amount of complex oxides and intermetallic compounds in the coating which make a brittle matrix it is recommended to use boride powders in a mechanical mixture with metal (alloy) powders.Institute of Problems of Materials Science, National Academy of Sciences of the Ukraine, Kiev. Translated from Poroshkovaya Metallurgiya, No. 5–6, pp. 54–60, May–June, 1994.     

Production and properties of brass-base P/M constructional materials. A review

Conclusions The best processing properties are exhibited by brass powders manufactured by the diffusional impregnation technique, using a zinc powder, brass swarf, or a copper-zinc master alloy as a point source. However, as this is a very labor-intensive process, normally preference should be given to melt atomization as a method of manufacture of brass powders. Brass P/M parts produced by the conventional method consisting of pressing a powder and sintering the resultant compacts have porosities of not less than 7–10%, and consequently this method is not widely used for the production of constructional brass parts. The sintering of compacts from copper and copper-zinc master alloy powders gives more stable zinc contents compared with the sintering of compacts from copper and zinc powders; the greatest stability of chemical composition is exhibited by sintered compacts from a homogenized brass powder. The formation of diffusional porosity accompanying the evaporation of zinc may be prevented by performing sintering in the presence of a liquid phase (which appears in the presence of a phosphorus or lead addition), saturating the sintering atmosphere with zinc vapor, and adding carbonates or halides of alkali and rare-earth metals to starting powders. The mechanical properties of materials can be markedly improved by eliminating their porosity. This may be achieved by subjecting porous preforms to hot forging, which enables brass P/M parts to be obtained whose mechanical properties are comparable to those of cast parts.Translated from Eoroshkovaya Metallurgiya, No. 3(255), pp. 56–64, March, 1984.