Study on Anti-tracking Properties of Unsaturated Polyester Resin SMC
A method of thickening hydroxyl-terminated unsaturated polyester with polyurethane (PU) that comes from the reaction between diisocyanate compounds and polyglycol is introduced, and the effect of PU prepolymer on the anti-arc properties of the sheet molding compounds (SMC) is studied according to the standard of ASTM, the electric strength is tested in the transformer oil under 423K, 453K, 473K, 523K respectively. The anti-tracking properties of UP-SMC were developed when Al(OH)3  and diisocyanate compounds were filled in UP-SMC. The microstructure of UP-SMC struck by electric arc was observed by means of SEM (Scanning Electron Microscopy). The results show that UP-SMC samples with no anti-tracking modification have some part of ablation and charring while the modified sample are with the low electric rot. The arc breakdown time would increase with the usage of PU. The SMC thickened by PU shows good aging resistance as well as anti-arc properties, it will be widely used on electrical parts and arc-deflecting cover of AC switch etc
Flame retarded polymeric material
The invention relates to a polymer material comprising a halogen-free flame-proofing agent incorporated into the polymer matrix, the flame-proofing agent comprising at least ammonium polyphosphate(s) and/or derivatives thereof and an oligomer or polymer 1,3,5-triazine derivative or mixtures of a plurality thereof and at least one compound selected from phosphates, pyrophosphates, polyphosphates, organic and inorganic phosphonates, organic and inorganic phosphinates, stannates, molybdates or borates of the elements of the main groups II, III, IV or of the sub-group elements Fe, Zn, Ti, Mn, Zr, Mo, pre-condensed melamine derivatives, melamine salts and addition compounds, ethylene diamine phosphate, piperazine phosphate, piperazine polyphosphate, 1,3,5-trihydroxyethyl isocyanurate, 1,3,5-triglycidyl isocyanurate and triallyl isocyanurate. The weight ratio of constituents A to constituents B is 10:1 to 1 :1, constituents A and B together amounting to between 60 and 99 wt. % and constituents C and D to between 1 and 40 wt. % of the total weight of constituents A, B, C and D. The polymer material is a thermoplastic elastomer (TPE).
Evolution of carbide precipitates in Hastelloy N joints during welding and post weld heat treatment
Abstract The effects of welding and post weld heat treatment (PWHT) on the morphology, composition and lattice parameter of the precipitates in the welding joints of Hastelloy N alloy have been investigated. Joint samples were prepared using a gas tungsten arc welding process with ERNiMo-2 fillers, and then solid-solution treated at 1100 °C for 20 min. After welding, eutectic M6C carbides can be observed in the heat affected zones (HAZ) and weld zones (WZ). These eutectic M6C carbides become spheroidized during the following PWHT. The concentration of Si decreases during the transformation from the primary ones to eutectic ones, and then increases during the spheroidizing process. The total concentration of Si + Cr in M6C carbides remains stable during welding and PWHT. At the same time, the heat leads to the outward diffusion of Mo from the M6C carbides, which results in a decrease of the lattice parameter.