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Composites based on iron powders clad with nickel and nickel–phosphorus are developed using modified methods such as thermochemical decomposition of diammonium phosphate, thermochemical synthesis in a vibrating layer, chemical phosphating, and reduction nickel salt with a sodium hypophosphite solution in both acid and alkaline media. The cladding of iron powders with phosphorus increases the magnetic flux density by 20% on average and permeability by 25% and promotes higher resistivity, thus decreasing magnetic losses. The coating partially remains on iron particles in composites based on powders clad with phosphorus in a vibrating layer or with nickel–phosphorus in acid media after high-temperature sintering. This decreases magnetic losses as well. Laboratory tests are performed to determine the corrosion resistance of iron powders before and after cladding using an accelerated drop analysis. It is established that phosphorus and nickel–phosphorus coatings increase the corrosion resistance by a factor of 2.5 to 3.0 apparently because protective phosphide layers form on iron particles. The materials based on iron powders clad with phosphorus and nickel–phosphorus differ from conventional ones in high magnetic properties, high corrosion resistance, and low magnetic losses at a frequency of 50 Hz and may be recommended for the manufacture of soft magnetic articles operating in both constant and alternating fields of power line frequency.

The technological processes of the fixing nickel, copper and tinny covering on particles of iron powder, applicable for fabrication magnetic-soft material by methods to powdered metallurgy are designed and explored. The magnetic characteristic magnetic-soft material, made from iron powder, particles which beforehand cover nickel or copper hang by nature covering, its composition, mode annealing temperature and so on are installed. Varying all these forming possible get magnetic-soft powdered material with necessary given characteristic.

HVP and HFPB of a prealloyed powder enable high-density Kh23N18 stainless steel to be obtained exhibiting good mechanical and corrosion properties. Such steel, when produced by any of the processes investigated, is superior in strength to cast steel; its elongation and corrosion resistance are comparable to or better than those of cast steel only when additional operations of presintering of blanks and diffusional annealing after hot plastic working are employed. The mechanical and corrosion characteristics of Kh23N18 steel produced by the HVP method from a mixture of iron, chromium, and nickel metal powders are satisfactory, but appreciably poorer than those of the same steel obtained from an alloy powder. Use of a prealloyed powder with a small carbonyl nickel powder addition in the manufacture of Kh23N18 steel by the HFPB method makes it possible markedly to activate the processes taking place during the presintering and short-time heating of porous blanks for HFPB, which manifests itself in an improvement in their strength and ductility characteristics. For the production of P/M Kh23N18 steel and other sintered stainless steels of the austenitic class on an industrial scale the hot-forging method is recommended, since it requires a simpler installation and enables parts of complex configuration to be produced.

Production of Kh13 steel by the HVP method without the presintering of porous blanks and final high-temperature diffusional annealing of dense compacts is possible only when an alloyed powder of the required composition is used. Use of a mixture of chromium and iron powders for the manufacture of Kh13 steel by the HVP process without additional operations — sintering of blanks and diffusional annealing of compacts does not give satisfactory results because diffusion processes cannot be completed during the short period of heating of blanks for HVP. With steel produced from an alloyed powder, the presintering of blanks and diffusional annealing of dense compacts after HVP are not essential because, while improving the mechanical characteristics of the steel, they decrease its corrosion resistance. The highest level of properties in dense P/M Kh13 steel, comparable to that characterizing cast steel of the same composition, is attainable only when a prealloyed powder is used in its manufacture. When such a powder is not available, a mixture of metallic iron and chromium powders can be employed, but the level of mechanical properties and corrosion resistance of the resultant steel will be much lower.

1. The presence of free structural carbon slightly lowers the corrosion resistance of iron-graphite alloys. The addition of Sulfides decreases their corrosion resistance by 15–20%. 2. Impregnation with machine oil or paraffin wax increases the corrosion resistance of porous sulfidized materials and enables their storage life to be extended 2–5 times. 3. At porosities below 10–12%, the weight gain of corrosion products is directly proportional to porosity. 4. The rate of corrosion of interparticle contacts in a porous material is 4–5 times higher than the rate of surface corrosion, and for this reason particular importance must be attached to the protection of porous articles against corrosion.

40Kh, Kh6, Kh13, and Kh30 chromium steel powders produced by the method of diffusion impregnation from point sources are homogeneous in composition and possess satisfactory compressibility and sinterability. Their corrosion resistance is comparable to that of cast steels of the same composition.

1. A study was made of the possibility of producing composite coatings from two nickel electrolytes at different pH values and temperatures. 2. It is demonstrated that the best nickel deposits with mullite whiskers are obtained in nickel sulfate electrolytes at low solution pH values (2–3) and a temperature of 25–30°C. 3. Mullite whiskers are readily incorporated into nickel electrodeposits. When an electrolyte contains up to 100 g/liter of mullite whiskers, the mullite whisker content of the resulting electrodeposit is up to 3 vol.%. 4. Studies were made of the high-temperature oxidation resistance of the composite coatings and of the effect of mullite additions on the microhardness of nickel electrodeposits.

1. The electroless nickel plating of sintered parts should not be performed in alkaline solutions. The best results were obtained by nickel plating in acid solutions (pH 5–5.2). 2. For obtaining nickel deposits 20–25μ thick, capable of resisting 3% NaCl solution for 7 h or longer, nickel plating should be performed in two stages. 3. In order to prevent the corrosion of the internal surface, the pores must be impregnated with GKZh-94 liquid before plating, and polymerization must be carried out. 4. For raising the corrosion resistance of the nickel deposit, the latter should also be impregnated with a weak solution of GKZh-94 and then subjected to polymerization. 5. If the nickel plating solution is to operate in a stable manner and be capable of correction, sodium citrate (15 g/liter) and glycocoll (30 g/liter) must be added to it. 6. The nickel plating solution is replaced by a fresh one after 5–6 operating cycles, when its phosphite content has reached 50–60 g/liter.

The investigation has shown that the bearing properties of hard-alloy coatings applied to constructional steel by the detonation technique from a powder mixture virtually match those of hard alloys produced by the powder metallurgy process. Such coatings can therefore be recommended for use in units operating under dry friction conditions.

1. A description is given of a new technique for the production of bimetallic iron-brass corrosion-resistant parts. The results are presented of experiments designed to study the conditions of preparation of brass coatings on sintered iron parts. The optimum temperature for the impregnation of a copper coating with zinc is 850–900°C. 2. The strength of brass-coated parts is characterized by the strength of the core, while the ductility of such parts is actually slightly higher than that of parts without a brass coating. 3. Tests have shown that the corrosion resistance of brass-coated sintered specimens in a humid-atmosphere chamber is the same as the corrosion resistance of specimens from dense brass.

1. The use of a zinc monophosphate solution for parkerizing sintered parts gives corrosion-resistant phosphate films which protect the outer surface against atmospheric corrosion. 2. Protection of the inner surface against corrosion requires pretreatment with steam or GKZh-94 (a 10% solution in gasoline), without subsequent sandblasting.

1. A technique has been developed for the preparation of granulated chromium carbide alloy powders, in which granules of a chromium carbide-nickel mixture are subjected to high-temperature sintering for 1.5 h at a temperature of 1400°C. 2. A process has also been evolved for the production of porous parts, including bushings, from loosely poured granulated chromium carbide alloy powders plated with a nickel-phosphorous alloy. It has been established that adequately strong parts of 40–45% porosity are obtained as a result of sintering for 1 h at 1120°C. It is shown that St. 3 steel cores must be used in the sintering of parts such as bushings. 3. A study was made of the gas permeability of porous specimens from granulated chromium carbide alloy powders. It is demonstrated that the gas permeability of porous parts from chromium carbide alloy powder is comparable to that of porous specimens from atomized spherical stainless steel powders.

1. A method is proposed for calculating the geometric dimensions of counterelectrodes (anodes) for the simultaneous deposition of electrophoretic coatings on cylindrical surfaces of different curvatures. 2. Using anodes calculated by this method, it is possible to apply chromium carbide coatings of uniform thickness and chemical composition to parts of complex configuration.

Elec t rophore t ic deposition is used as a means of applying wear res i s t an t coatings of hard alloys based on chromium carbide to steel par t s [1]. Now the rate of e lect rophoret ic deposition is known to depend strongly on the electrode voltage. However, in the coating of par ts of different s izes and geometr ic shapes it is also nec e s s a r y to allow for change in e lec t r ic field s t rength caused by t ransi t ion f rom one sys tem of electrodes to another.