Advanced Materials Research Vols. 328-330

Abstract: One of the two challenges about Supercritical Water-Cooled Reactor is material, especially for the fuel cladding. High temperature creep tests of Ni-based alloy C276, one of the candidate materials for the fuel cladding, were carried out at 650°C~750°C, with stress 130MPa~430MPa. The effects of temperature and stress on creep were investigated, the change laws of steady state creep rate with stress and time to rupture were analysed, and creep damage factors were separately calculated based on Kachanov’s formula and Norton’s formula. The results indicate that there exist two types of primary creep characteristics in C276: Type I creep characteristic at lower stress level and Type II at higher stress level respectively. C276 shows excellent high temperature creep resistance, and Kachanov’s damage factors D vs normalized time are basically coincident at 650°C, 700°C and 750°C. The damage obtained by Norton’s formula starts at about 40% of lifetime, and the damage factors calculated by Kachanov’s formula are relatively conservative.

Abstract: The evolution of microstructural morphology in semisolid A356 alloy was researched under the mechanical stirring. The results showed that there was the effect of the stirring time on the microstructural morphology of semisolid A356 alloy, in which the microstructural morphology became better with the stirring time prolonging. There was also the effect of the stirring process on the microstructural morphology, in which the microstructural morphology obtained from the melt cooling to the reset solid volume fraction to start stirring was coarser than that obtained from the stirring above the liquidus temperature, but the microstructural morphology rapidly changes under the shearing force.

Abstract: Si and Ge ions are implanted into SiO₂ thin films, subsequently the annealing treatment are carried out. The samples exhibit photoluminescence (PL) peaks at 400, 470, 550 and 780 nm. With the annealing temperature increasing, the intensity of 400-470 nm PL band increases remarkably. After oxidation annealing treatment, the intensity of 400-470 nm PL band decreases, and that of 550 nm and 780 nm PL peaks rises. Combing with the results of X-ray photoelectron spectroscopy(XPS), X-ray diffraction (XRD) and PL measurement, we propose that the PL peaks at 400 nm, 470 nm, 550 nm and 780 nm originate from ≡Ge−Si≡ center, ≡Si−Si≡ center, SPR center and GeO center, respectively.

Abstract: This paper carries out the research on the critical conditions of ferroelectric domain switch with different porosity and pressure. A micromechanics model is established with the influence of external electric field, stress load, domain wall energy and depolarization energy, etc. The results show that the domain switch critical dimension and nucleation energy decrease fastly in the initial stage and then decrease slowly as the reversed electric field evenly increases. The critical dimension and nucleation energy with different porosity and pressure are studied, too.

Abstract: For the study of new insensitive energetic material LLM-105`s coating and techniques, by means of theory analysis through the interface, calculation of the contact angle test, verified that EPDM can coat LLM-105. Booster samples were prepared by adopting water suspension method with EPDM is the adhesive. And the coating’s optimal technological condition is also be verified. The results showed that, the obtained LLM-105/EPDM booster can be coated better. The final results of the improved optimal technological condition is with vacuum degree is 0.03mpa, stirring speed is 430r/min, dropping speed is 0.06ml/min.

Abstract: Based on the JHC model of concrete damage evolution, the dynamic stress characteristics and failure mechanism of blast-hole near-field about different air-decked charge structures are studied by numerical simulation. Result shows that the failure mechanism of typical elements changes from compression-shear failure into shear-tensile failure gradually with the increase of their position in indirect initiation of both top-air-decked and bottom-air-decked charges, because of the affecting factors of the freedom and the loading from the hole. If middle-air-decked charges detonate from the top and bottom at the same time, loading and unloading waves in blasting hole are more influential to the damage of bottom elements than the surface freedom, because detonation waves of both top and bottom meet at the middle hole, so it is conducive to the media failure at the bottom hole, the elements of freedom surface have the same failure properties to top-air-decked charge.

Abstract: Infrared thermal imaging technology is a new nondestructive detection technology, which is widely used in pressure vessel detection. In this paper, three-dimensional temperature distribution model of pressure vessel with defects is established, and the influence factors on infrared detection of pressure vessel defect are researched. The influence of environmental factors, thermal excitation strength, thermal excitation time and defect size on infrared detection is analyzed. The results show that: (1) increasing thermal excitation can degrade the maximum reduced temperature when infrared radiation thermal excitation temperature is lower than 200°C, while the reduced temperature can be raised with the increased thermal excitation when the temperature is higher than 200°C. (2) the maximum comparison temperature increased first and decreased afterwards with the increasing thermal excitation time, finally reduce to the comparison temperature under steady state. (3) the influence of wind speed and surface blackness in environmental factors on infrared detection precision is greater.

Abstract: Based on the molecule design and energy absorption theory of polymer macromolecule materials, we synthesized a kind of multicomponents interpenetrating polymer network(IPN) which composed of polyurethane(PU), epoxy(EP) and unsaturated polymer resin(UPR). In order to further widen the damping temperature region of polymer materials, we introduced the polydimethylsiloxane (PDMS) into polyurethane(PU). Because of solubility parameter difference between PDMS and PU, we synthesized PDMS modified PU by blocking and grafting PDMS chain into PU main chain firstly. Then, a serious of interpenetrating polymer networks (IPN) which composed of PDMS-PU, EP and UPR were designed and synthesized. The damping performance and microstructure were characterized by using the spectrum of dynamic mechanical thermal analysis (DMTA) and the scanning electron microscope(SEM) respectively. The tested result indicated that the multicomponents IPN which modified by PDMS has wider temperature range and higher damping loss factor, and the PDMS grafting PU/EP/UPR shows good damping performance and microphase compatibility specially.

Abstract: To improve the surface quality and adhesion of diamond film is the key factors to realize CVD diamond coating widely applied in the wear-resistance parts field. Through optimizing deposition process parameters, the article used the straight wiredrawing chemical vapor deposition to depose the diamond film in the bore surface of WC-CO carbide wiredrawing mould. The surface topography of the coating, film quality and surface roughness were detected and the preparation of CVD diamond film coated wire drawing mould in drawing copper wires production line was applied. The experimental results show that working life of diamond film coated wire drawing mould improved to 40~ 50 of that traditional hard alloy mould, and the controlled copper wire had the better precision and surface quality.

Abstract: Ultrasonic methods are used in a wide variety of applications including medical studies, geological mapping, and nondestructive evaluation (NDE) tests. In the field of ultrasonic NDE, it is necessary to treat inverse problems of various types. The objective of this paper is to predict the flaw response in an inhomogeneous solid medium. A mathematical modelling of the testing situation is very valuable for a number of reasons. The modelling helps in developing physical intuition and in the interpretation of tests. Multi-Gaussian Beam (MGB) model is used to represent the incident ultrasonic beam. The effect of ultrasonic attenuation and phase velocity dispersion due to grain scattering is included in the predictions. The variation of received voltage is analyzed against the distance of the flaw from the transducer for different dimensions of a square cylinder void. The effect of variation of mean diameter of the grains on the received voltage for different domain of interest is also studied.