Corrosion properties of materials coated with Cr2O3/NiCr and with Cr2O3+NiCr functionally gradient materials

This paper studied the corrosion properties of five kinds of Cr₂O₃ coated materials: the SUS316L austenitic stainless steels respectively coated with the Cr₂O₃ layer (Cr₂O₃/316), Cr₂O₃ and 80Ni‐ 20Cr layers (Cr₂O₃/80NiCr/316), Cr₂O₃ and 50Ni‐ 50Cr layers (Cr₂O₃/50NiCr/316), Cr₂O₃ + 80Ni‐ 20Cr functionally gradient materials (Cr₂O₃ + 80NiCr FGM), and Cr₂O₃ + 50Ni‐ 50Cr FGM (Cr₂O₃ + 50NiCr FGM). All the coatings were made by atmospheric pressure plasma spraying method (APPS). The corrosion resistance of the coated materials was analyzed by immersion tests and electrochemical evaluations. A mechanism of the corrosion failures for these kinds of coated structures was proposed. The different coating structures for improving the adhesion between ceramics and substrates were assessed, and the effect of Cr content in the NiCr coatings on the corrosion property was discussed. The ceramic coatings with the 50Ni‐ 50Cr intermediate layer possessed a better corrosion resistance than that with 80Ni‐ 20Cr. The FGM structures appeared to offer weaker resistance to corrosion attack than that with the intermediate layer in general. Under corrosion test conditions, the corrosion‐proof abilities of the coated structures were, respectively: the Cr₂O₃/50NiCr/316 in the best rank; the Cr₂O₃/316, Cr₂O₃/80NiCr/316, and Cr₂O₃ + 50NiCr FGM in the second rank; and the Cr₂O₃ + 80NiCr FGM in the last rank. This means that applying the 50NiCr intermediate layer under the Cr₂O₃ ceramic coating can further improve the corrosion resistance of Cr₂O₃/316. Porosity analysis was used to explain the difference of corrosion resistance between the Cr₂O₃/50NiCr coated material and the Cr₂O₃ + 50NiCr FGM. The porosity in each layer of the Cr₂O₃ + 50NiCr FGM was higher than that in the Cr₂O₃/50NiCr coating, and as a result the corrosion resistance of Cr₂O₃/50Ni Cr/316 is better than Cr₂O₃ + 50NiCr FGM.     

Preparation of novel reactive plastisol based on poly(vinyl chloride) and multifunctional acryl esters

Poly(vinyl chloride) (PVC) powder was mixed with various polyfunctional acryl monomers as plasticizers to prepare acrylate‐modified plastisols. This class of plastisol was hardened into the B stage without reaction and then cured into a harder material through crosslinking of the acrylate. The best formulation was attained after evaluation of various acrylates, PVC grades, and peroxides. Several difunctional acrylates with solubility parameters similar to that of PVC could be most conveniently used as the plasticizer. A sheet molding compound was obtained by the combination of the resultant plastisols with glass fiber by compression molding using conventional machines. It was cured into a PVC‐based fiber reinforced plastic with high performance. This class of acrylate‐modified plastisol is called reactive plastisol. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1794–1801, 2000     

Epoxy resin particles, 2. An efficient synthetic method of epoxy resin particles in organic solvent by the aid of modified polyolefins as dispersant

Epoxy resin particles were efficiently prepared by addition of Bisphenol A diglycidyl ether to a solution of polyamine hardener in organic solvents containing polyolefin dispersants modified with maleic anhydride and maleimide. Aliphatic hydrocarbons and their mixtures with aromatic hydrocarbons were used as the reaction solvents. The size and size distribution of the particles could be controlled by modulating the difference in solubility parameter between the solvent and the polymer and by changing the reaction temperature. Smaller particles were formed when combined with more highly reactive amine hardeners. The particles prepared by this method showed a rough surface probably because of the polymer deposition on the finally formed particles in the final reprecipitation process. The present synthesis can afford an efficient method for manufacturing the epoxy resin particles in large scale.     

Effects of solvent addition to acetylation medium on cellulose triacetate prepared from low-grade hardwood dissolving pulp

As cellulose triacetate was prepared from low-grade hardwood-dissolving pulp, a considerable amount of the insoluble residue was present in the acetylation medium of the acetic acid/acetic anhydride/sulfuric acid system, and it consisted mainly of cellulose triacetate (CTA) and xylan diacetate (XDA). As one of the remedies for reducing the insoluble residue, a solvent was added to the acetylation medium and the effects of the solvent addition on the amount of insoluble residue formed were studied. To do so, 17 different solvents were selected so as to cover a wide range of solubility parameters. The obtained results clearly indicated that the addition of the solvent affects the amount of insoluble residue and that, excluding dichloroacetic acid, nitromethane was effective for its reduction, but that neither methylene chloride nor nitroethane were in spite of their effectiveness for softwood-dissolving pulp, which would be due to the intrinsic properties of XDA on the solubility in the acetylation medium. A new acetylation system with such an appropriate solvent would, therefore, provide a clue as to an industrial usage of the low-grade hardwood-dissolving pulps for cellulose acetate production. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1445–1449, 1998     

The effect of temperature on the unlubricated sliding wear of 5 CrNiMo steel against 40 MnB steel in the range 400–600°C

5 CrNiMo steel is used traditionally as hot forging die material in China. High temperature wear is a common failure mode of the steel. This paper deals with the sliding wear behavior of the steel in the temperature range 400°C to 600°C. The composition and features of the worn surface were analyzed using SEM, EDS and XRD. The oxidation of 5 CrNiMo steel under sliding wear condition at elevated temperature indicated that the oxide transfer layer formed on the sliding surface consisted of Fe₃O₄ and Fe₂O₃. The wear mechanism changed with the test temperature and the oxide transfer layer played an important part in the change in wear mechanism. At lower temperatures, wear was due to abrasive wear. From 500°C to 550°C, the oxide transfer layer presented a relatively compact morphology and the oxidational wear was the principal wear mechanism resulting in low wear rate at 500°C. When the test temperature was at 600°C, adhesive wear was predominant, and the wear rate increased greatly.     

Assessment of low-cycle fatigue life of Sn-3.5mass%Ag-X (X=Bi or Cu) alloy by strain range partitioning approach

The fatigue lives and damage mechanisms of Sn-Ag-X (X=Bi and Cu) solder alloys under creep-fatigue interaction mode have been investigated, and the adaptability of the strain partitioning approach to the creep-fatigue of these alloys was examined. Symmetrical and asymmetrical saw-tooth strain profiles components (i.e., fast-fast, fast-slow, slow-fast and slow-slow) were employed. Application of the slow slow,strain mode did not have an effect on fatigue lives of the alloys under investigation. Transgranular fracture observed on the fracture surfaces suggests that creep damage might be cancelled under slowslow mode. The fatigue lives of all alloys were dramatically reduced under slowfast mode, which is attributed to intergranular cavitation and fracture during tensile creep flow. On the other hand, the compression creep component generated by fast-slow mode also significantly reduced the life of Sn-3.5Ag and Sn-3.5Ag-1Cu, while the component did not affect the life of Sn-3.5Ag-xBi (x=2 and 5). The four partitioned strain ranges (i.e.,_{p, pp, cp}, and _cc) versus life relationships were established in all alloys tested. Thus, it is confirmed that the creep-fatigue life of these alloys can be quantitatively predicted by the strain partitioning approach for any type of inelastic strain cycling.     

Gate oxide integrity on ITOX-SIMOX substrates and influence of testdevice geometry on characterization

The integrity of gate oxides on low-dose separation by implanted oxygen (SIMOX) substrates fabricated by the internal-thermal-oxidation (ITOX) process, so-called ITOX-SIMOX substrates, was evaluated, and the influence of test device geometry on the characterization was investigated. Characterization of time-dependent dielectric breakdown (TDDB) was performed for a gate oxide of 8.6-nm thick using lateral test devices. Experimental results show considerable influence of gate electrode geometry on the gate oxide integrity (GOI) characteristics. This can be explained by a model that includes a lateral parasitic resistance in the superficial Si layer beneath the gate electrode. Based on analysis using this model, a test device with a small gate array was proposed to reduce the influence of lateral parasitic resistance, and the advantage of the device was verified     

Role of anions on heavy metal sorption of a cellulose modified with poly(glycidyl methacrylate) and polyethyleneimine.

The influence of anions on the equilibrium and kinetic uptake of heavy metals from an aqueous solution by a novel nitrogen-type chelating adsorbent was evaluated. Equilibrium experiments revealed that stoichiometric amounts of metals and anions are adsorbed by the resin. Kinetic studies showed that during the initial stage of adsorption, the anions are adsorbed by the adsorbent prior to the metal ions. This occurred almost simultaneously with an increase in solution pH. At equilibrium, the pH returned towards its initial value. The concentration of anion also fluctuated during the entire equilibration process. Following these observations, mechanisms governing the role of anions on enhancing capacity and rate of metal uptake of this type of chelating adsorbent type were established.     

配电系统二线短路时故障电流抑制效果的模拟

研究了在配电系统中引入限流器后的系统行为。假设二线短路故障分别发生在电源侧母线出口和负荷馈线末端,在三点分别设置了限流器,利用ＥＭＴＰ软件对限流器的故障电流抑制效果进行了模拟。结果表明限流器的引入具有明显的限流效果,并可改善因故障引起的母线电压瞬时降低。     

Dissociation of FAK/p130(CAS)/c-Src complex during mitosis: role of mitosis-specific serine phosphorylation of FAK

At mitosis, focal adhesions disassemble and the signal transduction from focal adhesions is inactivated. We have found that components of focal adhesions including focal adhesion kinase (FAK), paxillin, and p130(CAS) (CAS) are serine/threonine phosphorylated during mitosis when all three proteins are tyrosine dephosphorylated. Mitosis-specific phosphorylation continues past cytokinesis and is reversed during post-mitotic cell spreading. We have found two significant alterations in FAK-mediated signal transduction during mitosis. First, the association of FAK with CAS or c-Src is greatly inhibited, with levels decreasing to 16 and 13% of the interphase levels, respectively. Second, mitotic FAK shows decreased binding to a peptide mimicking the cytoplasmic domain of beta-integrin when compared with FAK of interphase cells. Mitosis-specific phosphorylation is responsible for the disruption of FAK/CAS binding because dephosphorylation of mitotic FAK in vitro by protein serine/threonine phosphatase 1 restores the ability of FAK to associate with CAS, though not with c-Src. These results suggest that mitosis-specific modification of FAK uncouples signal transduction pathways involving integrin, CAS, and c-Src, and may maintain FAK in an inactive state until post-mitotic spreading.