Analysis of Remagnetization Processes of High-Anisotropic Alloy after Heat Treatment

The simulation of the Sm(Co, Fe, Cu, Zr)7.5 type alloy domain structure formation after various thermal treatments was carried out by FMRM program based on a phenomenological approach to the analysis of the uniaxial highly anisotropic ferromagnets demagnetization processes. It is shown that the domain structure of the alloy in the thermally demagnetized state expands as the coercive force of the alloy decreases. It is noted that the domains size increasing process is associated not only with a decrease in the coercive force but also with a change in the influence of the magnetostatic interaction.

pengaruh penekanan pellet silika terhadap porositas dan permeabilitas

Klasifikasi silika (SiO2) dibagi dalam empat karakter dasar silika yaitu struktur kristal, dispersitas, komposisi permukaan dan porositas. Sebelumnya pasir silika ini banyak digunakan oleh industri minyak dan gas sebagai proppant (pasir frak) maupun sebagai filter air. Pilihan proppant tergantung pada jenis permeabilitas atau kekuatan butir yang dibutuhkan. Dimana proppant dengan ukuran yang lebih besar akan memberikan permeabilitas rekahan yang lebih baik, karena nilai permeabilitas akan meningkat seiring dengan bertambahnya diameter dari butiran. Penelitian ini bertujuan untuk mengetahui pengaruh penekanan pellet silika terhadap porositas dan permeabilitas. Penekanan pellet silika ini menggunakan mesin press hidrolik dengan type KW05-135 dan kapasitas 10.000 Kg. Peneliti membuat pellet silika dengan kandungan pasir silika berukuran butir seragam (100 mesh) sebanyak 8,74 g/cm3, menggunakan perekat jenis Polyethylene Glycol (PEG) 400 sebanyak 0,57 g/cm3, dan Aluminium Powder 3,42 g/cm3. Cetakan yang digunakan Mold Pellet Silika Type Alloy 410 dengan diameter dalam 27 mm, diameter luar 57 mm dan ketinggian lubang cetakan 89 mm dengan penekanan 1000 Kg, 3000 Kg, dan 5000 Kg, serta memberikan suhu sintering sebesar 1200°C. Adapun nilai porositas optimum yang diperoleh sebesar 39,25% dan nilai permeabilitas optimum yang di dapatkan sebesar 57 mD.

Nanocrystallization and phase formation in Fe73.5Nb3Cu1Si15.5B7 amorphous ribbon under laser heating

Laser-induced local crystallization in Finemet-type alloy was studied using X-ray diffraction, SEM and EDX methods. For investigated conditions of irradiation (wavelength λ = 1.06 µm, laser power density 50 W/cm2), it was found that primary crystallization starts with the formation of the nanocrystalline α-Fe(Si) solid solution at shorter exposure time and the second step crystallization with the nanocrystalline hexagonal H-phase formation occurs in longer exposure time. Changes in the local element concentration were observed at the surface of the irradiated zone and at the ribbon fracture. It was shown that the nonlinear temperature field due to the laser irradiation resulted in changes of the local elements concentration and this feature changed crystallization mechanism of the Finemet-type alloy.

Temperature rise of LaNi5-based alloys by hydrogen absorption

The temperature rise of AB5-type alloy by hydrogen absorption was limited by their critical temperatures (Tc). We found the relation between H2 desorption temperatures of metal hydrides at atmospheric pressure...

Friction stir welding machine “Malakhit”

Friction stir welding unit is described, designed for experimental works on the welding technology of large-sized items. Structural diagrams of the main units of the installation are presented. Technical characteristics of unit make it possible to obtain prototypes of weld made of aluminum AMg5 type alloy with thickness of up to 20 mm, with weld length of 2000 mm in the longitudinal direction and 1500 mm in the transverse direction. The maximum trans verse dimensions of the welded structures is 1500 Ѕ800 mm. The parameters of the welding process in real time are displayed on the control panel and recorded in the report: the values of the vertical force on the tool, the power consumed by the electric drive of the spindle and the horizontal force on the welding table in the direction of welding.

Influence of impurity and alloying elements on high temperature oxidation resistance of E110 type zirconium alloys

The structural-phase state has been investigated and content of oxygen and hydrogen in the E110 type alloy after high-temperature oxidation simulating an accident of the LOCA type has been determined. Tubular samples with a diameter of 9.13 mm and a wall thickness of 0.7 mm from the Zr—1% Nb alloy obtained on the electrolytic zirconium basis (E110), the zirconium sponge basis (E110G), and from a modified alloy Zr—1% Nb—0.12% Fe—0.13% O (E110M) were selected for the study. The samples were subjected to a steam oxidation at a temperature of 1100 °C to 18% local oxidation depth. It was found that the E110G alloy based on a zirconium sponge absorbed oxygen and hydrogen less under LOCA conditions.