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Residual stress is a key factor affecting the properties of ceramic/metal brazed joints. In this work, the residual stress of sapphire/Ti6Al4V alloy joints brazed with CuTi+B composite filler after cooling and reheated to 400 °C was calculated by finite element numerical simulation method. The effect of the B content in the filler and the filler thickness on the residual stress distribution of brazed joints after cooling was studied. The results show that the residual stress is mainly concentrated in the area near the filler layer. The maximum von Mises stress is located in the filler layer and a large Z-axial (the direction perpendicular to the brazed surface) tensile stress is on the sapphire near the filler layer. The B content and the filler thickness have no significant effect on the distribution of residual stress, but they have a certain effect on the value of residual stress of the sapphire near the filler layer. The von Mises stress and the Z-axial stress of this area increase with the increase of B content, and they decrease first and then increases with the increase of filler thickness. When the sapphire/Ti6Al4V joint is reheated to 400 °C, its residual stress significantly reduces and the residual stress on the periphery of the filler layer changes from compressive stress to tensile stress. As the B content is 1 and 3 wt%, the sapphire/Ti6Al4V joint with a smaller residual stress can be obtained. The microstructure observation and shear tests of the joints show that cracks appear in the high stress concentration area and the fracture starts from the area with maximum axial tensile stress, which verifies the accuracy of the simulation results. [ABSTRACT FROM AUTHOR]

Wood-decaying fungi on living trees in China were surveyed over the last 12 years. In all, 102 potentially pathogenic Basidiomycetes were found in natural forests, forest plantations, parks and gardens, and among them 20 species were recorded for the first time on living trees in China. The host(s), occurrence, type of damage, type of decay and distribution of each species in China are given. Most of these wood-destroying fungi are polypores in the Aphyllophorales, and the majority were found in temperate and boreal forests. Of all the species detected, 88 species are known to cause white rot, and 14 cause brown rot; 25 species are considered as common, 44 occasional, and 33 rare. [ABSTRACT FROM AUTHOR]

Twenty-one basidiocarp specimens of Heterobasidion annosum s.l. were collected in six forest areas in western and central China, from host trees Picea schrenkiana, Abies fabri, Abies fargesii and Larix griffithii. Single-spore cultures were isolated from the basidiocarps and identified by mating tests. All the specimens proved to belong to the species Heterobasidion parviporum. The results show that this fungus has a wide distribution in China. It seems to be a less aggressive pathogen in China than in Europe, although reliable data on the occurrence of Heterobasidion root rot in coniferous forests of China are so far lacking. [ABSTRACT FROM AUTHOR]