Predicting the efficiency of high-speed diamond grinding of superhard materials using 3D models of macro-and micro-levels

Owing to its extreme hardness, chemical stability and robustness, conductive diamond is an attractive material for scanning tunneling microscopy (STM). The selection of a suitable diamond and preparation of the STM tip is a challenge because electrically conductive diamonds can be grown using various methods and have anisotropic properties. A new method for the selection of conductive diamonds that is based on the registration and analysis of the tunneling I-V (TIV) characteristics of the tunnel junction between the diamond tip and graphite (0 0 0 1) surface at a constant tunneling gap is proposed. TIV should be monotonous while the tunneling currents vary from 0.1 to 6 nA with increasing bias voltages from 0.05 to 1 V. We found that HPHT diamonds grown in the Fe -Al-C-B growth system are more suitable for STM probs compared to grown in the Fe-Co-C-B system.

The study is devoted to structure and mechanical properties of a diamond composite used for manufacturing of cutting tools applied in a wide range of technological fields. The sample tools were fabricated by cold-pressing technology followed by hot-pressing in vacuum of the 51Fe–32Cu–9Ni–8Sn matrix mixture with diamond bits, both in absence and presence of nano-VN additives. It was demonstrated that without VN addition, the diamond–matrix interface contained voids and discontinuities. Nanodispersed VN added to the matrix resulted in the formation of a more fine-grained structure consisting of solid solutions composed of iron, copper, nickel, vanadium and tin in different ratios and the formation of a tight diamond–matrix zone with no visible voids, discontinuities and other defects. Optimal concentrations of VN in the CDM matrix were found achieving the maximum values of nanohardness H = 7.8 GPa, elastic modulus E = 213 GPa, resistance to elastic deformation expressed by ratio H/E = 0.0366, plastic deformation resistance H3/E2 = 10.46 MPa, ultimate flexural strength Rbm = 1110 MPa, and compressive strength Rcm = 1410 MPa. As-prepared Fe–Cu–Ni–Sn–VN composites with enhanced physical and mechanical properties are suitable for cutting tools of increased durability and improved performance.

Development of expert system for the process of high-speed diamond grinding of superhard materials based on macro

Enhanced operability of nuclear fuel rod cylindrical cladding made with thin protective nanoengineered coatings

The paper describes a practical method for real-time measurement of active power in a dielectric barrier discharge by calculating a Lissajous figures based on the Manley formula. Such a method is very useful for controlling the output ozone concentration in ozone generators taking into account the active power in a DBD reactor. A dielectric barrier discharge (DBD) in atmospheric pressure air was excited by a high-voltage pulse power supply. The active power of the reactor was estimated from the area of the Lissajous figure formed by the V-Q traces, which is directly proportional to the energy consumed per cycle at voltages of 8 and 12 kV, respectively.

A BSTRACT . Currently, much attention is paid to the treatment of industrial wastewater, which would provide the necessary degree of decontamination for organizing a recycled water supply and further disposal of the treatment-generated by-product. The paper presents an advanced technology using a new nanomaterial that decreases initial concentrations of heavy metal ions in electroplating production wastewater from 25 g/L to less than 0.6 mg/L. An integrated process of wastewater treatment consists of two stages: energy- and resource-efficient ferritization followed by sorption onto suspensions of nanopowders of polyvalent iron oxides. The advantages of an electromagnetic pulse method for achieving ferritization at frequencies up to 0.9 kHz in comparison with expensive thermal treatment at temperatures up to 75 °C are demonstrated. The polyvalent iron oxide nanosorbents were obtained by electroerosion dispersion. The result of the integrated treatment is that the purified water meets the requirements for water reuse in electroplating production. The treatment-generated by-product has high chemical stability and a significant content of magnetic ferrite phases, thus having a high potential for further utilization. In contrast to the widely used reagent-based treatment of concentrated wastewater contaminated by heavy metals (> 25 g/L), the integrated method developed here prevents environmental contamination by toxic effluents and ensures the rational use of water and energy inputs in the system of industrial production.

The article examines the cutting characteristics of the developed composite material based on aluminum oxide micropowders with silicon carbide nanopowder additives obtained with the help of electric sintering. The influence of thermal conductivity of the developed composite Al2O3-SiC based material on the wear and durability of the material in application of cutting tool is examined, and a comparison with the traditional cutting ceramic tool materials is made. Considering that the process of cutting with ceramic inserts is carried out without the cutting fluids, the heat removal improvement from the cutting zone makes it possible to increase the tool life. It is proposed to use the thermomechanical parameter B for a comparative assessment of cutting ceramic composite material characteristics.

The generalized approaches of mathematical modelling for numerical simulating and processing of measured electrical signals from board sensors installed on wheeled electro-mechanical platforms are developed in this research. The mathematical backgrounds of the developed approaches are elaborated on the basis of especially formulated initial-value problems need to be solved numerically or the identification procedure need to be applied. It is shown that using the Lagrange's formalism and the electro-mechanical analogies for constructing the improved coupled mathematical models both the mechanics and electrics and electronics of the wheeled platforms and the installed board sensors and the measuring electronic transducers allows having the more information if processing of the measured signals will be on the basis of such improved mathematical models. It is considered the particular example of using the proposed approaches dealt with simulating and processing the measured electric signals from the board accelerometer installed on the four wheeled electro-mechanic platform. Due to this example it was shown that using of the improved mathematical models allows the significantly wider possibilities of accelerometer measuring, so that the different parameters can be estimated by means processing the direct accelerometer measures using the corresponded mathematical models. It was shown that, the most difficulties of identification problems for processing the measured signals from the board sensors installed on the wheeled platforms are due to inherent them the mathematical incorrectness according to Hadamard. The effectiveness of using the filtering of the results of processing the measured signals is shown for the considered particular example of the identification problem also.

Influence of plasma-based ion implantation and deposition on the structure, internal stress and mechanical properties of nanocrystalline ZrN coatings

Structure and pinning centres in MgB 2 bulk

Nanomechanical and I-V characterization of a conductive coating on an HPHT diamond substrate

It is proposed the approach for estimating the impact of thin protective coatings on the stress-strain state of the thick-walled claddings of cylindrical fuel rods considering internal and external pressures from fission products and moving heat carrier in a nuclear reactor core. This approach is used for quantitative estimations the impact of possible thin coatings made from a stainless steel on the stress-strain state of the cladding made from the Zirconium-based alloy used in the WWER-1000 nuclear reactors. It is shown that thin protective coatings can allow increasing the general strength and reliability of the cladding due to stresses decreasing.

The natural frequencies and the modes of the radial oscillations are computed by using the method of grids for the cylindrical claddings made with the thin protective coatings for the fuel rods of the nuclear reactors. It is received the values more than 150 kHz for first natural frequencies of the radial oscillations of the claddings of fuel rods of the WWER-1000 nuclear reactors. It is shown that the thin protective coatings lead to noticeable increasing of first natural oscillation frequency, but have negligible influencing on the second and higher natural frequencies as well as on the modes of the radial oscillations of the claddings of fuel rods.

Nanostructured ZrO 2 ceramic PVD coatings on Nd-Fe-B permanent magnets