材料期刊网

Electrical Conductivity and Sensitive Characteristics of Ag-Added BaTiO₃-CuO Mixed Oxide for CO₂ Gas Sensing

A.M. El-Sayed F.M. Ismail S.M. Yakout

材料科学技术（英文）

Carbon dioxide gas sensors based on BaTiO₃-CuO composite with different concentrations of Ag addition (1, 1.5 and 2 wt%) have been prepared by stander ceramic method and sintered at 500 and 700°C for 5 h. Electrical conductivity and gas sensing properties of the prepared samples were investigated. Electrical conductivity measurement was used to characterize the obtained sintered sensor pellets. It was found that electrical conductivity and the sensitivity to CO₂ were improved with Ag addition and sintering. The correlation between Ag content at different sintering temperature and sensing characteristics towards CO₂ is discussed.

关键词: BaTiO₃-CuO composite; Ag addition

Electrical Conductivity and Sensitive Characteristics of Ag-Added BaTiO₃-CuO Mixed Oxide for CO₂ Gas Sensing

A.M. El-Sayed F.M. Ismail S.M. Yakout

材料科学技术（英文）

Carbon dioxide gas sensors based on BaTiO₃-CuO composite with different concentrations of Ag addition (1, 1.5 and 2 wt%) have been prepared by stander ceramic method and sintered at 500 and 700°C for 5 h. Electrical conductivity and gas sensing properties of the prepared samples were investigated. Electrical conductivity measurement was used to characterize the obtained sintered sensor pellets. It was found that electrical conductivity and the sensitivity to CO₂ were improved with Ag addition and sintering. The correlation between Ag content at different sintering temperature and sensing characteristics towards CO₂ is discussed.

关键词: BaTiO₃-CuO composite; Ag addition

Hot Deformation Behavior of Modified CNS-Ⅱ F/M Steel

YANG Ying , YAN Qing-zhi , GE Chang-chun

钢铁研究学报(英文版)

Modified CNS-Ⅱ F/M steel was designed for in-core components of supercritical water cooled reactor. Study on the hot deformation behavior of modified CNS-Ⅱ F/M steel is of great importance for processing parameter planning and microstructure controlling during hot deformation. The hot deformation behavior of modified CNS-Ⅱ F/M steel was investigated through isothermal hot compression test at temperature ranging from 1223 to 1373 K and strain rate 001 to 10 s-1. The true stress-true strain data gained from compression tests were used to built constitutive equation of modified CNS-Ⅱ F/M steel. The influence of strain on the accuracy of constitutive analysis was incorporated, assuming strain has a influence on material constants. A 5th order polynominal equation with very good accuracy was used to represent the influence of strain on material constant. The flow stresses calculated from the constitutive equation were compared with test values in the whole experiment range and the absolute average error for the constitutive equation in predicting flow stress is 4728%. At last, the recrystallization behavior of modified CNS-Ⅱ F/M steel was investigated. The relationship of critical strain and peak strain with Zener-Hollomon parameter were given by an experimental equation.

关键词: F/M steel , constitutive equation , dynamic recrystallization

Effect of Heat Treatment Process on Mechanical Properties and Microstructure of Modified CNS-Ⅱ F/M Steel

YANG Ying , YAN Qing-zhi , MA Rong , GE Chang-chun

钢铁研究学报(英文版)

Ferritic/martensitic (F/M) steels have been recommended as one of the candidate materials for supercritical water cooled reactor (SCWR) in-core components use for its high thermal conductivity, low thermal expansion coefficient and inherently good dimensional stability under irradiation condition in comparison to austenitic steel. CNS-Ⅱ F/M steel which has good mechanical properties was one of the 9-12Cr F/M steels designed for SCWR in the previous work. In this study a modified CNS-Ⅱ F/M steel was used and it′s ultimate tensile strength was 925 MPa at room temperature and 483 MPa at 600 ℃ after optimizing heat treatment parameter. The ductile to brittle transition temperature of modified CNS-Ⅱ F/M steel is -55 ℃. Those are at the same level or even higher than that of CNS-Ⅱ and some commercial F/M steels nominated for SCWR in-core component use. The transmission electron microscope (TEM) results showed that the mechanical properties of the tempered martensite was closely related to the decomposition stage of the martensite.

关键词: supercritical water reactor , ferritic/martensitic steel , cladding material

超塑性 m-δ关系

刘勤 , 周善佑

材料研究学报

超塑性m-δ关系曲线可以分为m_L=m_(max)和m_L=m_(min)两大类型。均可由下面的C.L.(刘勤)m-σ方程表示:σ(%)=〔cε~(m-m_0)-1〕×100当σ=σ_0=0时,m=m_0≠0,C=C_0=κ_0/κ_0=1。当σ=σ_1(σ_(11),σ_(12),σ_(13),…,)时,m=m_1(m_(11),m_(12),m_(13),…),C=C_1(C_(11),C_(12),C_(13),…)=κ_1(κ_(11),κ_(12),κ_(13),…)/κ_0,当σ=σ_F时,m=m_F,C=C_F=κ_F/κ_0。对C 值进行“规划”,得到的C_1~(σ_O-σ_L)-(m_L=m_(max)),C_2~(σ_F-σ_L)-(m_L=m_(min)),C_3~(m_0-m_L)-(m_L=m_(max)和C_4~(m_F-m_L)-(m_L=m_(min))四种类型的“规划”方程分别对m_L=m_(max)和m_L=m_(min)型m-σ曲线适用。若m-σ曲线属简单的下降式,C 及其“规划”值均可近似地取1。否则,C-σ关系是应加以研究的问题。m 和k 值对σ值的效应可以分为动态(直接)和静态(间接)两种。最后的σ值是两种效应的综合结果。(注:m 和κ值见基本方程σ=κε~m)

关键词:

12Cr-F/M钢在超临界水中的腐蚀行为

沈朝 , 段振刚 , 孙耀 , 张乐福 , 徐雪莲

腐蚀与防护

采用慢应变速率试验(SSRT)研究了12C>F/M钢在25 MPa,550℃和650℃的超临界水(SCW)中的机械性能,以及在550℃的SCW中的应力腐蚀开裂(SCC)倾向.同时通过均匀腐蚀试验研究了12Cr-F/M钢在550℃/25MPa的SCW中的腐蚀性能.SSRT结果表明,12Cr-F/M钢在550℃/25 MPa时具有优良的机械性能,当温度升高到650 ℃时其机械强度下降明显,但延伸率基本不变.由断口SEM形貌可知,12Cr-F/M钢具有沿晶应力腐蚀开裂(IGSCC)倾向.均匀腐蚀结果表明,12CpF/M钢在550℃/25MPa的SCW中的腐蚀性能较差,其腐蚀增重呈现出抛物线生长规律,1 000 h后其腐蚀增重达741mg/dm2.同时发现其在600 h时表面氧化膜出现裂纹,1 000 h时后观察到氧化膜发生剥落,而氧化膜脱落主要是因为在降温过程中基体与氧化物间不一致的热膨胀系数造成的.

关键词: 腐蚀 , 应力腐蚀开裂 , 机械性能 , 超临界水

微量元素对低偏析合金M17F的高温氧化性能的影响

胡武生 , 沈嘉年 , 李铁藩 , 彭晓 , 马信清 , 李美栓 , 周龙江

腐蚀学报（英文）

静态空气中氧化实验表明,低偏析镍基铸造高温合金M17F比普通镍基铸造高温合金M17F'(M17F的基础上+0.005%P、0.10%S和0.10%Zr)具有更低的恒温氧化增重速率,但氧化膜的粘附性更差。XRD、SEM和EDAX分析实验表明,两合金氧化膜的组成和结构基本相同。分析认为,M17F'合金中相对高含量的S、P和Zr的共同作用加速了该合金氧化膜的生长,另外该合金中0.1%含量的活性元素Zr改善了氧化膜的粘附性。

关键词: 低偏析镍基铸造高温合金 , null , null

Secondary M6C precipitation in K40S cobalt-base alloy

Materials Letters

Secondary M,C precipitation was investigated in K40S cobalt-base alloy after 100 h aging at 950 degreesC. The results showed that it was closely related to the tungsten-rich zones inherited from the as-cast condition and the degeneration of the primary M7C3 carbide. A direct element reaction, 6M + C --> M6C, in which C comes from the decomposition of the M7C3 carbides, is suggested as the mechanism of secondary M6C precipitation in K40S alloy. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词: M6C precipitation;aging;M7C3 carbide;superalloy

Chemical bonding and mechanical properties of M(2)AC (M = Ti, V, Cr, A = Al, Si, P, S) ceramics from first-principles investigations

Journal of Materials Research

MAX-phase carbides (M is an early transition metal, A is an A-group element) exhibit an interesting bonding characteristic of alternative stacking of strong M-C bonds and relatively weak M-A bonds in one direction. In the present first-principles total energy calculations, we establish the relationship between mechanical properties and electronic structure for ternary M(2)AC (M = Ti, V, Cr. A = Al, Si, P, S) carbides. By systematically tuning elements on the M and A sites, pronounced enhancements of bulk modulus, elastic stiffness, and ideal shear strength are achieved in V-containing V(2)AC (A = Al, Si, P, and S) carbides. It is suggested that tailoring on the A site is more efficient than on the M site in strengthening the mechanical properties of studied serial carbides. The results highlight a general trend for tailor-made mechanical properties of ternary M(2)AC carbides by control of chemical bonding.

关键词: strength;solids;shear;dislocations;ti3sic2

m（M）/m（P）比值对磷酸镁水泥干燥收缩的影响及机理研究?

戴丰乐 , 齐召庆 , 汪宏涛 , 姜自超 , 张时豪 , 丁建华

功能材料 doi:10.3969/j.issn.1001-9731.2016.12.022

研究了m(M)/m(P)比值对磷酸镁水泥干燥收缩行为的影响，采用温度记录仪、压汞仪、X 射线衍射仪、扫描电镜及能谱仪等分析手段探讨了m(M)/m(P)比值对磷酸镁水泥干燥收缩的作用机理。结果表明，随着m(M)/m(P)比值的增大，磷酸镁水泥水化初期的膨胀量以及干燥收缩减小；水化8 h左右水泥开始收缩，龄期达到20 d左右收缩趋于稳定；磷酸镁水泥收缩量的减少，是由于m(M)/m(P)比值的增大导致磷酸镁水泥水化温度降低，孔隙率增大，水化产物MgKPO4?6 H2 O 减少，水化产物结构趋于疏松。

关键词: 磷酸镁水泥 , 干燥收缩 , m(M)/m(P)比值