Densification by cold re-pressing of low-carbon managese steels

YesObtaining closed porosity, i.e. densities >7.4 g.cm-3, is a major target in PM development. To increase density, strength and surface hardness of low-carbon PM steels: cold and warm compaction, sintering and slow cooling through the ferrite transformation region, followed by cold repressing and surface hardening were investigated. The slow cooling resulted in soft, ferritic, microstructure amenable to cold resizing. Repressing at 700-900 MPa densified the samples to ~7.6 g.cm-3. Mechanical properties, after repressing and surface hardening, are characterised by appreciable plasticity following macroscopic yielding at stresses of 400-1200 MPa. Reference is made to possible further increases in strength by incorporation of small additions of clean, fine Mn containing master alloy into the powder mix. Results were verified industrially on hollow cylinders made from Fe-0.5Mo or Fe-1.5Cr-0.2Mo base powders

Synthesis and structure of BiFeO3:RE (RE=Gd3+, Dy3+, Nd3+) ceramics

In the present work the influence of rare earth elements concentration (0-10at-%) on BiFeO3:RE (RE=Gd3+, Dy3+, Nd3+) ceramics were studied. All ceramic powders were synthesized by conventional ceramic method using high purity raw materials (>99,9%), and subsequently sintered by free sintering and cold pressing method. To analyze the powders and ceramics more the XRD, EDS, SEM, and DTA were performed

Recovery of oil with unsaturated fatty acids and polyphenols from chaenomelessinensis (Thouin) Koehne: Process optimization of pilot-scale subcritical fluid assisted extraction

The potential effects of three modern extraction technologies (cold-pressing, microwaves and subcritical fluids) on the recovery of oil from Chaenomelessinensis (Thouin) Koehne seeds have been evaluated and compared to those of conventional chemical extraction methods (Soxhlet extraction). This oil contains unsaturated fatty acids and polyphenols. Subcritical fluid extraction (SbFE) provided the highest yield—25.79 g oil/100 g dry seeds—of the three methods. Moreover, the fatty acid composition in the oil samples was analysed using gas chromatography–mass spectrometry. This analysis showed that the percentages of monounsaturated (46.61%), and polyunsaturated fatty acids (42.14%), after applying SbFE were higher than those obtained by Soxhlet, cold-pressing or microwave-assisted extraction. In addition, the oil obtained under optimized SbFE conditions (35 min extraction at 35 °C with four extraction cycles), showed significant polyphenol (527.36 mg GAE/kg oil), and flavonoid (15.32 mg RE/kg oil), content, had a good appearance and was of high quality

Application of Pressure Treatment Methods for Solid Processing of Silumin Chip Waste

n this article various technological schemes for processing waste in the form of chips of an alloy of an aluminum-silicon system are presented. It was noted that the processing of fine waste of the chips type is always accompanied by oxidation of the metal due to the large surface of contact with the air. To eliminate the loss of metal into oxides during re-melting, this study proposes processing chips by pressing to obtain briquettes (a method of hot extrusion is meant by ‘pressing’). Processing involves the receipt of briquettes from rods. The processes of cold and hot briquetting were undertaken separately. The results of applying the scheme using real production waste are presented in this study. The tensile strength achieved was up to 270 MPa. The relative elongation to rupture was 10–25% and the area reduction after rupture was 25–45%. There were no large differences in the use of briquettes obtained by cold processing and hot processing. The conclusion is drawn about the overall effectiveness of the application of the waste processing without the use of the metal melting. Keywords: silumin, shavings, extrusion, plastic deformation, heat treatmen

Method of making carbide/fluoride/silver composites

A composition containing 30 to 70 percent chromium carbide, 5 to 20 percent soft noble metal, 5 to 20 percent metal fluorides, and 20 to 60 percent metal binder is used in a powdered metallurgy process for the production of self-lubricating components, such as bearings. The use of the material allows the self-lubricating bearing to maintain its low friction properties over an extended range of operating temperatures

Method of producing porous tungsten ionizers for ion rocket engines Patent

Method for producing porous tungsten plates for ionizing cesium compounds for propulsion of ion engine

Strength and High-Temperature Stability of Dispersion Strengthened Nickel-MgO Alloys

Strength and high-temperature stability of dispersion strengthened nickel-magnesium oxide alloy

Minimizing water and energy consumptions in water and heat exchange networks.

This study presents a mathematical programming formulation for the design of water and heat exchangers networks based on a two-step methodology. First, an MILP (mixed integer linear programming) procedure is used to solve the water and energy allocation problem regarding several objectives. The first step of the design method involves four criteria to be taken into account., ie, fresh water consumption (F1), energy consumption (F2), interconnection number (F3) and number of heat exchangers (F4). The multiobjective optimization Min [F1, F2] is solved by the so-called ɛ-constraint method and leads to several Pareto fronts for fixed numbers of connections and heat exchangers. The second step consists in improving the best results of the first phase with energy integration into the water network. This stage is solved by an MINLP procedure in order to minimize an objective cost function. Two examples reported in the dedicated literature serve as test bench cases to apply the proposed two-step approach. The results show that the simultaneous consideration of the abovementioned objectives is more realistic than the only minimization of fresh water consumption. Indeed, the optimal network does not necessarily correspond to the structure that reaches the fresh water target. For a real paper mill plant, energy consumption decreases of almost 20% as compared with previous studies