Study of the Interaction of Adhesion-Active Copper-Silver Alloy PSR-40 with Stainless Steel of the Austenitic Class

Interaction of molten copper-silver alloy PSR-40 with stainless steel 1Kh18N9T is studied in relation to melt temperature (700-800°C) and contact time (10-40 min). It is established that alloy components diffuse into the steel. The depth of their penetration and the degree of interaction with steel increase with an increase in temperature and contact time. As a result of this with contact of the structural components to more than 20 min and a temperature above 780°C there is formation of chemical compounds with a higher hardness at the alloy-steel interface. Therefore impregnation in air for porous carcasses made from stainless steel 1Kh18N9T fibers with molten copper-silver alloy above these parameters is undesirable.     

Effects of Copper Powder Bearing Material Composition on Working Characteristics

Effects have been established for phosphorus and lead on the working characteristics of tinned bronze with high-speed operation (up to 20000 rpm or up to 2 m/sec) at low pressures (up to 2.0 MPa). It has been found that Cu - Sn - Pb - CP powder bearing material, where CP is a copper-phosphorus alloy, under such conditions has a lower coefficient of friction than does tinned bronze and a much higher wear resistance, while sliding bearings based on it have high working life. A microheterogeneous structure is formed in this material: an α-solid solution of tin in copper, along the boundaries of which there is uniformly distributed a strengthening phase (network of copper phosphide Cu₃P with inclusions of the phosphide eutectic Cu₃P + Cu₃Sn + (Cu - Sn), and there are lead inclusions at the grain boundaries intersections. This material has very good tribotechnical characteristics at high rotation speeds and low pressures and also low coefficient of friction, low wear, and consequently long working life of bearings made of it.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 120–126, March–April, 2005.     

We have lost the right to work unprofitably

Tulachermet. Translated from Metallurg, No. 9, pp. 4–6, September, 1992.     

Relationship between Erosion and Mechanical Characteristics of Fine-Grained Hard Alloy WC – 16% Co Obtained by Solid-Phase and Liquid-Phase Consolidation. Part 1. Erosion Resistance

We have studied the erosion characteristics of hard alloys under electrospark alloying conditions, and the relationship of such characteristics with the physical and mechanical properties. WC – 16% Co alloys were obtained by conventional sintering under vacuum in the temperature range 950-1350°C, and by sintering followed by high-energy pressure treatment at the same temperatures. We have shown that the erosion resistance depends ambiguously on the porosity and bending strength but is quite clearly connected with the crack resistance and the electrical resistivity which in turn is determined by the quality of the interphase and intergrain boundaries. We have refined the structural dependence of the erosion resistance of hard-alloy electrodes. This dependence is manifested to the same extent as the structural dependence of the electrical resistance.     

Relationship between Erosion and Mechanical Characteristics of Fine-Grained Hard Alloy WC – 16% Co Obtained by Solid-Phase and Liquid-Phase Consolidation. Part 2. Mass Transfer (Cathode Mass Gain and Transfer Coefficient)

We investigate the erosion characteristics of hard alloys in spark alloying and their relation to the physical and mechanical properties. The WC – 16% Co alloys used were made by traditional vacuum sintering in the temperature range 950-1350°C or by sintering with subsequent high-energy treatment under pressure at the same temperatures. We show that how efficiently protective hard alloy coatings are formed on the substrate depends in more than one way on the porosity and the bending strength, definitely depends on the cracking resistance of the alloys, but is most clearly related to the resistivity which in turn is determined by the quality of the phase and grain boundaries. In addition, a linear relationship exists between the cathode mass gain, the transfer coefficient, and the erosion of the anode material. We demonstrate experimentally that the erosion resistance of hard alloys is a structure-sensitive characteristic to the extent that the structural factors affect the resistance.     

High-Q Microwave Dielectric Materials Based on the Spinel Mg2TiO4

Composite ceramics based on the spinel Mg₂TiO₄ were prepared by a conventional mixed-oxide route. To achieve the temperature stabilization of the dielectric constant, each of the composites was added with 7 mol% CaTiO₃. The effect of the substitution of isovalent Co for Mg on the microstructure and the microwave dielectric properties of the composite ceramics was also investigated. A maximum Q × f value of around 150–160 THz was obtained for the undoped Mg₂TiO₄, whereas a reduced Q × f value was observed for an increase in the Co concentration in the system (1− x )Mg₂TiO₄− x Co₂TiO₄. Upon doping with 7 mol% CaTiO₃, the Q × f value passed through a maximum with increasing Co concentration. Adding ZnO–B₂O₃ to the composite system based on Co-doped Mg₂TiO₄ resulted in a reduction of the sintering temperature by 150°–200°C without any significant degradation in the Q × f value.     

Effect of feeding Ca–Mg–RE–Zr composite cored wire during refining of liquid steel on weldability of ultrahigh strength wear resistant steels

The weldability and mechanical properties of an ultrahigh strength wear resistant steel were substantially improved by the addition of a small amount of Ca–Mg–RE–Zr composite (1·5 kg t^?1) to the molten steel during the refining stage. Based on optical and electron microscopy examinations, the observed improvements were attributed to the enhanced pining effect of inclusions on the original austenite grain boundaries within the coarse grained heat affected zone, as well as the inclusion induced acicular ferrite formation within the fine grained heat affected zone.     

Visible and NIR Upconverting Er3+–Yb3+ Luminescent Nanorattles and Other Hybrid PMO‐Inorganic Structures for In Vivo Nanothermometry

Lanthanide‐doped luminescent nanoparticles are an appealing system for nanothermometry with biomedical applications due to their sensitivity, reliability, and minimal invasive thermal sensing properties. Here, four unique hybrid organic–inorganic materials prepared by combining β‐NaGdF₄ and PMOs (periodic mesoporous organosilica) or mSiO₂ (mesoporous silica) are proposed. PMO/mSiO₂ materials are excellent candidates for biological/biomedical applications as they show high biocompatibility with the human body. On the other hand, the β‐NaGdF₄ matrix is an excellent host for doping lanthanide ions, even at very low concentrations with yet very efficient luminescence properties. A new type of Er³⁺–Yb³⁺ upconversion luminescence nanothermometers operating both in the visible and near infrared regime is proposed. Both spectral ranges permit promising thermometry performance even in aqueous environment. It is additionally confirmed that these hybrid materials are non‐toxic to cells, which makes them very promising candidates for real biomedical thermometry applications. In several of these materials, the presence of additional voids leaves space for future theranostic or combined thermometry and drug delivery applications in the hybrid nanostructures.     

Adhesive Strength of Material Joints for Orthopaedic Stomatology

Wetting, adhesion, and adhesive strength of a stainless steel substrate with SINMA plastic and MK porcelain are studied. It is shown that clean and plasma-sprayed substrates are readily wetted with plastic at temperatures less than 800 K and with porcelain at 1450 K. It is established that plasma-sprayed dentures with a plastic facing have an adhesive strength greater by a factor of three to five compared with conventional dentures.     

Production of Thermally Stable Erosion-Resistant Coatings on Carbon Fibers by Chemical Deposition from a Gas Phase Using Volatile Coordination Compounds of Metals

Protective coatings of heat-resistant metals and their oxides or oxycarbides on carbon fibers were obtained by chemical deposition from a gas phase of metallic coordination compounds. Deposition products considered were mixtures of the oxides and oxycarbides of aluminum and hafnium. A low deposition temperature creates the preconditions for the solution of a number of scientific -technical problems. Two versions of the method were considered and analyzed.