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The material prescription, potential distribution, contamination trend and surface insulating properties under contamination and lightning conditions for the ceramic long rod insulator are investigated. The surface contamination trend of the ceramic long rod insulator can be fitted to an exponential function in a low rainfall area. Potential distribution calculation by three-dimensional finite element method shows that over 50% operating voltage concentrates on the single unit of high-voltage polarity for the long rod insulator string, which is more uneven in comparison with the disc ceramic insulator string. Five-hundred kilovolt full-scale artificial pollution test demonstrates that the contamination flashover voltage of the ceramic long rod insulator has a negative exponential relationship with equivalent salt deposit density and a linear relation with string length. A lightning impulse discharge test confirmed that the relation between 50% lightning impulse discharge voltage and dry arcing dis...

Binary Fe-Al alloy ingots with 29 at. %Al were prepared with commercially pure Fe and Al in a vacuum induction furnace. The specimens used in the internal friction measurement were cut using an electric sparkle machine from the ingots into a dimension 68×1.7×0.9 mm3. The heat treatment was performed in such regimes as heating temperature 900°C and holding time 1 hour in an argon atmosphere followed by furnace cooling or air cooling. The air-cooled samples were then aged at 350°C for different time to achieve the different degree of disorder. The internal fiction-temperature spectra of the air-cooled Fe71Al29alloy were measured during both heating and cooling using a computer-controlled automatic inverted torsion pendulum through free-decay and forced vibration methods. It has been found that three internal friction peaks appear during heating at 180°C termed as P1, 340°C termed as P2 and 510°C termed as P3 in air-cooled specimens, respectively. P1 and P2 peaks disappear and P3 is retained during cooling. XRD results show that the air-cooled Fe71Al29alloy is disordered and the furnace-cooled specimen possesses ordered structures. The air-cooled specimen presents similar diffraction peaks to the furnace-cooled specimen after it is heated to 650°C and then in-situ cooled to room temperature. Ageing has great influence on the P1 and P2 peaks for the air-cooled Fe71Al29alloy. The height of P1 and P2 peaks is decreased with increasing aging time, which is due to the reduction in the disorder degree of the air-cooled specimen.

The static friction characteristic was investigated in the case of litchi picker’s clamp heads made of PVC plastic, silicone and rubber, carved with textures of circular, sawtooth, plain and grid, when in contact with litchi stalks. An experimental device was developed and used to measure the static coefficient of friction between a flat surface and cylinder. Clamp heads made of rubber were found to have the biggest static coefficient of friction, and clamp heads made of PVC plastic were found to have the smallest static coefficient of friction. Clamp heads carved with circular texture were found to have the biggest static coefficient of friction, and clamp heads carved with grid texture were found to have the smallest static coefficient of friction. And for specimens of different sizes, the bigger the diameter, the bigger the static coefficient of friction. Results suggest that the best clamp heads for a litchi picker are made of rubber, carved with circular texture, and a bigger clamping force i...

The low frequency damping capacity of a strained Fe-31.36Mn-3.15Si (wt.%) alloy has been investigated using a multifunctional internal friction apparatus (MFIFA) through the free decay and forced vibration method. The high damping source is proposed to have originated from the irreversible movements of e/γ boundaries, being amplitude-dependent damping. An internal friction peak appears on the internal friction-temperature curves at about 280°C during heating from room temperature to 400 °C and the peak height is drastically reduced during subsequent in situ cooling. The peak height increases with increasing T/f. It has been suggested that the internal friction peak is resulted from the e → γ transformation during heating.

Low-frequency internal friction investigation of reverse martensitic transformation in oil-quenched Ni64Al36 alloy has been carried out using a multifunctional internal friction apparatus from room temperature to 400 °C and additionally differential scanning calorimetry and X-ray diffraction experiments were also completed. It has been shown that an internal friction peak presents at about 220 °C in the internal friction–temperature curve during heating for the oil-quenched Ni64Al36 alloy but not for the furnace-cooled Ni64Al36 alloy. The peak still appears during cooling and the peak temperature shifts to lower temperature. The changes of the peak temperature positions cannot be visibly observed when the vibration frequency is changed. The peak heights increase with decreasing vibration frequency and increasing heating rate, being linearly directly proportional to It has been suggested that the internal friction peak results from reverse martensitic transformation of L10 γ during heating and originates from martensitic transformation of γ L10 during the subsequent cooling process. The influence of the thermal cycles on the transformation is not observed for the limited thermal cycles. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Hydroxyapatite (HA)–316L stainless steel composite biomaterials with different 316L stainless steel fibre volume fraction in the composite were fabricated by hot pressing and sintering at elevated temperature. 316L stainless steel fibres were enwrapped in the HA matrix with integration being very tight. Metallographic microscope, SEM and EDAX analysis were carried out in order to investigate the microstructure in the materials and the combination interface between HA and 316L stainless steel fibre was observed in detail. While the composite contained 20 vol.-%316L stainless steel fibre, the bending strength and the compressive strength are equal to ∼200 MPa and 400 MPa, respectively. The research displayed that mechanical properties increase with the increase in volume of the 316L stainless steel fibres, but decrease with increasing diameter and mean length of the fibres. Toughness of the composite increases with the rise of 316L stainless steel contents. It has been shown that some Fe atom diffus...

The magnetomechanical hysteresis damping of Fe-Al alloys has been investigated using a computer-controlled automatic inverted torsion pendulum. It has been shown that Al content and heat treatment have a significant effect on the magnetomechanical hysteresis damping of the alloys. The Fe-10.5 (at.%)Al alloy has an optimal damping capacity after it was air-cooled from 900°C and the Fe-Al alloys with 29(at.)%Al and 38(at.)%Al exhibit rather low damping capacity after undergoing the same heat treatment because of decreasing magnetism. The water-quenched or as-cast specimens cannot form high damping due to high internal stress. An appropriate heating temperature in heat treatments is essential to obtain high damping.