Advanced Materials Research Vol. 502

Abstract: In order to measure thickness and Study on growth behaviors of oxide layers on grinding wheel surface in ELID, the measurement system consisted of a laser sensor and an eddy current sensor was constructed to do a preliminary research on oxide layer replaced by rust. Through the comparison of the values of the thickness obtained by measurement system and the electron microscope of high precision, in this paper, the accuracy of the measurement result and the feasibility of the system ware verified.

Abstract: From the visual condition, steel corrosion status, chloride content,concrete strength and other aspects, reinforecd concrete structures after electrochemical chloride extraction treatment nearly 10 years were surveyed and detected, and the results showed that the structure surface had a good appearance and no obvious deterioration,the content of chloride ions in concrete was low, the content of chloride ions around rebar areas was far lower than the critical value,the rebar remained in fully passive condition, the electrochemical chloride extraction treatment had no significant influence on the concrete strength, the seal coat on the structure surface was relative complete, but the aging phenomenon such as color alteration, adhesion strength reduction etc. was found on the surface, except for some discoloration and reduced adhesion strength.

Abstract: The Mechanism of 304 Stainless Steel Pitting Corrosion Was Researched in Chloride Ions Environment. the Metallographic Microstructure of Areas near the Pitting Corrosion and Far Away from the Pitting Corrosion Were Observed by the Metallographic Experiment；Cr Content of the Sample Was Determined by EDXRF, to Prove Chloride Ion Impact on the Element Cr of 304 Stainless Steel. Finally, Corrosion Rate of Specimens Was Determined by Piecewise Experiment Method to Prove Otherness for Corrosion Rate in Different Period of 304 Stainless Steel in Chloride Ions Environment.

Abstract: The interfacial fracture strength in polymer blends is investigated in this study. The constitutive relations of polymeric matrix and inclusions are both approximately described by linear viscoelastic models. It is assumed that the interfacial de-boding between inclusions and matrix is dominantly induced by the hydrostatic component of remote stress. Based on the assumption, the interfacial de-bonding of a viscoelastic inclusion embedded in an infinite polymeric matrix is analyzed. It is found that the size of inclusion will strongly affect the magnitude of critical stress, and the effect of Poisson’s ratio on the de-bonding is so small that can be ignored.

Abstract: The PANI-PVA composite conductive coatings adopt PVA as the base material together with the doping of hydrochloride (HCl), dodecylbenzenesulfonic acid (DBSA), the aminosulfonic acid (NH2SO3H ) aqueous solution were prepared. The influences of PVA content, acid content, oxidant content, reaction time and drying temperature of film on the conductivity of coating film were studied. The result shows that the conductivity of HCl-PANI-PVA coating film is the highest among them in case the PVA content is 40% and the drying temperature of film is 80°C. The maximum conductivity of HCl-PANI-PVA coating film is 15.0S/cm in case the C(HC1)=0.5mol/L, the reaction time is 6 hours and the n(APS/An)=1.0; the maximum conductivity of DBSA-PANI-PVA coating film is 7.1S/cm in case the C(DBSA)=1.0mol/L, the reaction time is 8 hours and the n(APS/An)=2.0; the maximum conductivity of NH2SO3H-PANI-PVA coating film is 2.0 S/cm in case the C(NH2SO3H)=1.0mol/L, the reaction time is 6 hours and the n(APS/An)=2.0.

Abstract: Polyaniline(PANI) with the doping of hydrochloride(HC1), aminosulfonic acid (NH2SO3H) or dodecylbenzenesulfonic acid(DBSA) was prepared by in-situ polymerization. Effects of acid content, reaction time, oxidant ammonium persulfate (APS) dosage and reaction temperature on the conductivity of PANI were studied. The resistance and thermal stability of them were compared. Results show that the largest conductivity of HC1-PANI is 1.98 s.cm-1 among them in case the C(HC1)=0.5mol/L, reaction time is 6.0h, n(APS/aniline)=1.0; The conductivity of NH2SO3H-PANI is 0.2s.cm-1 in case the C(NH2SO3H)=1.0mol/L, reaction time is 6.0h, n(APS/aniline)=2.0; The conductivity of DBSA-PANI is 0.98s.cm-1 in case the C(DBSA)=1.0 mol/L, reaction time is 8.0h, n(APS/aniline) = 2.0. The the least resistance of HC1-PANI is 10Ω, and that of NH2SO3H- PANI is the largest of 120Ω. The order of their thermal stability is DBSA-PANI > NH2SO3H-PANI > HC1-PANI before 350°C, that of their thermal stability is inverse when it reaches 350°C.

Abstract: Galling is a known failure mechanism in many sheet metal forming processes. It limits the lifetime of tools and the quality of the products is affected. In this study, U-channel stamping experiments are performed to investigate the galling behavior of the advanced high strength steels in sheet metal forming . The sheet materials used in the tests are DP590 and DP780. In addition to the DP steels, the mild steel B170P1 is tested as a reference material in this study. Experimental results indicate that galling problem becomes severe in the forming process and the galling tendency can be divided into three different stages. The results also show that sheet material and tool hardness have crucial effects on galling performance in the forming of advanced high strength steels. In this study, DP780 results in the most heaviest galling among the three types of sheet materials. Galling performance are improved with increased hardness of the forming tool.

Abstract: A reduced model was used to simulate the CVI process from methane. The scale of the preform was 120mm in diameter and 90mm in height. A random pore model was used to describe the evolution of pores in preform. Parameters such as temperatures and pressures were studied to research the deposition process. Effects of these two parameters are similar but have different impact mechanisms according to the analysis of results. Temperature impacts the reaction rate to improve the efficiency of deposition, while pressure impacts the concentrations of all hydrocarbon and then improves the total amount of carbon which also results in an increase of density.

Abstract: In this paper, by using the commercial finite-element software of ProCAST, unidirectional solidification processes in 23t steel ingot were simulated. Emphasis is placed on analysis of required time for complete solidification of steel ingot and temperature distribution about ingot and side wall during the solidification process. By comparing simulation values and measured values of side wall during the solidification process, the simulated results conclusively demonstrate that our developed model is feasible and valuable.