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(2006) Liu, H.L.; Huang, C.Z.; Wang, Jun; Teng, X.Journal ArticleTwo kinds of Al2O3/Ti(C0.7N0.3) nanocomposites were fabricated with traditional hot pressed sintering and repetitious-hot-pressing technology, one is added with nano-scale SiC, and the other is without SiC. The results showed that the mechanical properties of the former are higher than that of the latter, especially the fracture toughness can reach up to 8.3 MPa m1/2. Although the fracture toughness remains high, repetitious-hot-pressing results in the reduction of flexural strength. The improvement of the mechanical properties is interpreted from the different microstructure and fracture mode. The microstructure shows that the addition of nano-scale Ti(C0.7N0.3) and nano-scale SiC lead to the refinement of matrix grain, and the inter/intragranular microstructure can be formed instead of the intergranular microstructure in monolithic alumina. The higher fracture toughness resulted mainly from the transgranular fracture mode.
(2006) Sun, J.; Huang, C.Z.; Wang, Jun; Liu, H.L.Journal Article20 wt% TiN/3Y-TZP mixed with an amount of less than 15 wt% Al2O3 particles has been fabricated by hot-pressing techniques, and the mechanical properties and microstructure were investigated. There is a good chemical compatibility among ZrO2, TiN and Al2O3 and the addition of 5 wt% Al2O3 can improve the densification of composites. Al2O3 particles have little effect on improving flexural strength but have a distinct effect on toughening for 20 wt% TiN/3Y-TZP, which may be due to the residual stresses and microcracks resulting from the mismatch between the expansion coefficients of Al2O3 and ZrO2. An amount of 5 wt% Al2O3 in 20 wt% TiN/3Y-TZP can improve the bonding strength among grains and change the fracture pattern from intergranular to transgranular fracture.
(2006) Sun, Y.; Wang, Jun; Guo, D.M.Journal ArticleReal-time parametric interpolation has played a key role in the computer control of machine tools. To achieve highest quality parts, generated trajectories not only describe the desired toolpath accurately, but also have smooth dynamics profiles. This paper presents a novel parametric interpolator based on guide curve. The relationships between geometric properties and kinematic properties are firstly discussed. Then, with a consideration of the important effect of the curvature of curvilinear path on the machining dynamics, a corresponding formula, which describes the relation of the maximum allowed feed acceleration/deceleration and the maximum allowed rate of change of curvature radius of paths, is built. Thus, based on a near arc parameterization and through modifying the curvature radius curve to deal with corners, key regions and other cases, adaptive feedrate schedule is completed according to the reconstructed smooth curvature radius curve. Consequently, confined chord errors, corners on the path and the acceleration/deceleration capabilities of the machine tool are simultaneously considered and incorporated into the guide curve based parametric interpolation system without using look-ahead scheme. Simulation results indicate the feasibility and precision of the proposed interpolation method.
(2006) McAlpine, Iain; Reidsema, Carl; Allen, BelindaConference Paper
(2006) Lacis, Mikel; Kanapathipillai, SangarapillaiConference PaperExcessive noise radiated by pipes consisting of air or steam are often lagged using porous materials of high flow resistivity and impervious sheets usually made from metals and plastics. This paper looks at the prediction of insertion loss associated with the lagging of cylindrical pipes. A method is described and a program to efficiently calculate the predicted insertion loss as a function of frequency is developed. Predicted values of the insertion loss are compared with measured values found in past literature. Accompanying this is a comparison of the predicted values compared with current recognised theoretical results. Finally an in-depth parametric study is presented.