Materials Literature
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On-line Partial Discharge (PD) testing of rotating machines has traditionally been carried out using pre-installed High Voltage Coupling Capacitor (HVCC) sensors connected at the terminal box of the machine. These provide high impedance to low frequency signals (; 10 MHz). The use of these sensors allows PD measuremen…
In order to research the difference of the partial discharge in the inter-turn insulation of transformers under different voltage forms, a discharge test platform is established to simulate the inter-turn discharge. By using constant AC voltage method and increasing voltage method, the partial discharge is detected by…
Water accumulation in the hollow space of a maxillary obturator is a continuing problem, and it is unclear whether the porosity of acrylic resin is involved in the mechanism. The purposes of the study were to evaluate the effect of a hollow space in the resin obturator on water sorption under a thermal cycle and to de…
Ω-shaped copper specimens were oxidized in a tube furnace with wet air at 1 atm. and inlet gas-flow rates from 0.01 to 1.4 l/min at 500 °C for 4 hours. Scanning electronic microscope (SEM) results show that the density of nanowires formed on the surface of specimens during oxidation is significantly related to inlet g…
The specific heat, magnetization, and magnetic susceptibility of TlErSe 2 have been studied in the temperature range 77–300 K. The main thermodynamic functions of TlErSe 2 , namely, the changes of entropy and enthalpy, have been determined from the temperature dependence of the specific heat.
Multilayered prototypes of Al and Ag total reflection mirrors with a protective coating of amorphous ZrO 2 oxide were analyzed using transmission electron (cross-sectional method), optical, and scanning (with electron probe microanalysis) microscopes. The prototypes’ reflectivity was measured by the recording of refle…
Superfine, high-purity and well-distributed magnesium aluminate spinel powders were fabricated by controlling alkoxides hydrolysis process. Magnesium aluminate alkoxides were prepared by sol-gel with magnesium, aluminum and n-butyl alcohol as starting materials. Magnesium aluminate spinel powders were fabricated by do…
The paper presents operational characteristics of a small induction motor with the stator core made of amorphous laminations, supplied from mains or frequency inverter at 50, 100 and 200 Hz. Calculations were performed using field-circuit and equivalent circuit approaches taking account of non-linearity and additional…
The space charge distribution of the polymer is an important factor affecting the insulating properties. This paper studies the characteristics of space charge distribution of SiC/LDPE nanocomposites surface modified by the coupling agent KH-560. The experimental results show that the interface between the nano-SiC pa…
Creep corrosion is a mass transport process in which solid corrosion products (typically sulfide) migrate over a surface. The corrosion product creeps onto the solder mask surface and causes short circuits between the adjacent pads and traces. Creep corrosion of electronic assemblies is a growing problem. Commonly see…
One of the most serious problems for the development of multilayer ceramic capacitors (MLCCs) is that their electrical resistance decreases under long-term DC voltage. Oxygen vacancy migration in BaTiO 3 is thought to be one cause of this deterioration. In this study, to understand this mechanism, quantitative analysi…
The dielectric response of reduced 1.0 mol %-Ni-doped KTaO 3 single crystals was studied to determine the mechanism of the high dielectric constant of 160000, with a low dielectric loss of less than 0.1. The dielectric constant depends on the sample thickness, sample color, and electrode material. The obtained results…
A method of synthesis of a polynuclear cobalt(II) complex with carboxylated Boltorn H20, a hyperbranched polyol of second generation, has been suggested. The logarithm of stability constant and the composition of the complex species BH20(OC(O)CH 2 CH 2 COO) 12 Co 12 in a 50% acetone solution have been calculated from…
Crystal-oriented 1-mol% Li 2 O-excess (Na 0.51 K 0.47 Li 0.02 )(Nb 0.8 Ta 0.2 )O 3 (NKLNT) was manufactured from variously-sized NaNbO 3 (NN) templates via reactive template grain growth. The effect of NN template size was investigated in regard to the degree of orientation and the piezoelectric properties of NKLNT. A…
Considerando-se as dificuldades para a utilização de MgO em concretos refratários, técnicas anti-hidratação têm sido propostas com o objetivo de minimizar os efeitos deletérios causados pela reação da magnésia com a água. Em paralelo, surge a necessidade de investigar novas metodologias que permitam melhor avaliar os…
Graphene with different surface morphologies were fabricated on 8°-off-axis and on-axis 4H-SiC(0001) substrates by high-temperature thermal decompositions. Graphene grown on Si-terminated 8°-off-axis 4H-SiC(0001) shows lower Hall mobility than the counterpart of on-axis SiC substrates. The terrace width is not respons…
This paper addresses the influence of carbon nanotubes (CNT) on the structure and mechanical properties of high tensile strength thermoplastic polymer fibers. Polyamide (PA) fibers with different draw ratios, with and without CNTs as fillers, and having mechanical properties close to industrial standards were spun in…
Lead-free Li x (K 0.5 Na 0.5 ) 1- x (Nb 0.8 Ta 0.2 )O 3 piezoelectric ceramics samples prepared by the conventional solid-state reaction and two-step calcination method were achieved and compared. The effects of the amount of Li 2 O 3 on the phase structure, microstructure, dielectric, and piezoelectric properties of…
A new 1D polyoxovanadate containing boric acid [Cu(en) 2 V 10 O 28 ][Cu(en) 2 (H 2 O)] 2 2H 3 BO 3 2H 2 O (1, en=ethylenediamine) has been hydrothermally synthesized and structurally characterized. Compound 1 consists of a polyoxovanadate chain [Cu(en)2V 10 O 4- 28 ]n based on the linkage of decavanadate clusters and…
We report on compression behaviors of oil-immersed insulating pressed-boards used in transformers for analyzing the axial vibration of windings. We examined the compression stress-strain curves of oil-immersed pressed-boards. We found that compression behaviors depended on strain rates and temperatures, that is, visco…