The effect of (Ti + Al): V ratio on the structure and oxidation behaviour of TiAlN/VN nano-scale multilayer coatings

Nano-scaled multilayered TiAlN/VN coatings have been grown on stainless steel and M2 high speed steel substrates at U-B = - 85 V in an industrial, four target, Hauzer HTC 1000 coater using combined cathodic steered arc etching/unbalanced magnetron sputtering. X-ray diffraction (XRD) has been used to investigate the effects of process parameters (Target Power) on texture evolution (using texture parameter T*), development of residual stress (sin(2) psi method) and nano-scale multilayer period. The composition of the coating was determined using energy dispersive X-ray analysis. The thermal behaviour of the coatings in air was studied using thermo-gravimetric analysis, XRD and scanning electron microscopy. The bi-layer period varied between 2.8 and 3.1 nm and in all cases a {1 1 0} texture developed with a maximum value T* = 4.9. The residual stress varied between -5.2 and -7.4 GPa. The onset of rapid oxidation occurred between 628 and 645 degreesC depending on the (Ti+Al):V ratio. After oxidation in air at 550 degreesC AlVO4, TiO2 and V2O5 Phases were identified by XRD with the AlVO4, TiO2 being the major phases. The formation of AlVO4 appears to disrupt the formation of Al2O3 which imparts oxidation resistance to TiAlN based coatings. Increasing the temperature to 600 and 640 degreesC led to a dramatic increase in the formation of V2O5 which was highly oriented (0 0 1) with a plate-like morphology. At 640 degreesC there was no evidence of the coating on XRD. Increasing the temperature to 670 degreesC led to further formation of AlVO4 and a dramatic reduction in V2O5. (C) 2003 Elsevier B.V. All rights reserved

ВЛИЯНИЕ ТРАНСПОРТНыХ ЗАДЕРЖЕК ШЛАМОВыХ ПОТОКОВ НА ПРОДОЛЖИТЕЛЬНОСТЬ НЕСТАЦИОНАРНОГО РЕЖИМА РАБОТы ВОДНО-ШЛАМОВыХ СИСТЕМ

Проблема и ее связь с научными и практическими задачами. Все подре-шетные воды гравитационного отделения аккумулируются в зумпфах большой емкости и далее перекачиваются на операцию предварительной регенерации в гидроциклоны, классификаторы или сгустители. При этом необходимо обеспе-чить подачу на самую верхнюю отметку для дальнейшего распределения шла-мовых потоков самотеком. Как правило, такие потоки характеризуются высо-кими транспортными задержками. Магистрали для шламовых потоков перед узлами вывода имеют меньшие геометрические размеры, переносят незначи-тельное количество пульпы по сравнению с вводными коммуникациями

Spectrum and Variability of Mrk501 as observed by the CAT Imaging Telescope

The CAT Imaging Telescope has observed the BL Lac object Markarian 501 between March and August 1997. We report here on the variability over this time including several large flares. We present also preliminary spectra for all these data, for the low emission state, and for the largest flare.Comment: 4 pages, 4 figures, Late