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1.
在乙腈介质中合成了苯并-12-冠-4(简称B-12-C-4)和单环己基-12-冠-4(简称Cy-12-C-4)的六种希土配合物:RE(NO3)3·B-12-C-4(RE=Pr,Gd,Yb,Lu),RE(NO3)3·Cy-12-C-4(RE=La,Lu).研究了它们的IR及1HNMR性质,并测定了四种单晶的结构.用INDO法计算了Lu(NO3)3·B-12-C-4,Lu(NO3)3·Cy-12-C-4的电子结构.结果表明.B-12-C-4与希土的配合物稳定性按Pr,Gd,Yb,Lu顺序减弱,并且Cy-12-C-4与希土的配位能力大于B-12-C-4.发现冠醚分子通过自身不同程度的扭曲,改变冠醚环空穴的大小,实现与不同大小的希土离子的配位作用.  相似文献   

2.
将稀土氮碳硼共渗技术应有和于45钢制CYB-57TH-7.3-1.2型整体抽油噘筒的表面处理,可使内径57mm、长度7300mm的整体泵筒在直线度基本不变、径向总变形量小于0.050mm的前提下,获得层深达0.4mm,表面最高硬度940~1050HV的稀土氮碳硼渗层,其性能指标达到或超过了美国API标准。油田实验结果表明,在含砂量高、腐蚀严重的稠油井中,其泵效和使用寿命明显高于镀铬和引进美国技术的  相似文献   

3.
尿素-NaBr-KBr熔体中钴及稀土-钴的电沉积   总被引:3,自引:0,他引:3  
稀土-钴合金具有许多优异性能,可用于制作磁性、磁光…等功能材料。日本学者研究了在有机电解液中电沉积Co-Gd薄膜,未见前人研究低温熔盐体系中电沉积稀土合金的报道。尿素-(79mol%)-NaBr(19.5mol%)-KBr(1.5mol%)的熔点为51℃,可在100℃左右下作为电解介质。在尿素熔体中加入BaOAc,能增加Co ̄(2+)还原为Co的阴极极化。因此选择100℃的尿素-NaBr-KBr-NaOAc作为本底熔体,研究Co ̄(2+)的电还原,镧、铽、镝、铥各自与钴的电解共沉积。在所研究的熔体中,Co ̄(2+)一步不可逆还原为Co。测定Co ̄(2+)+2e=Co反应的传递系数α为0.45,Co ̄(2+)在熔体中的扩散系数为2.5×10 ̄(-6)cm ̄2·s ̄(-1)。稀土离子还原为稀土金属的电位很负,以致在本底熔体分解前未出现阴极波。但在含COCl_2熔体中加入REC_3(LaCl_3、TbCl_3、DyCl_3、TmCl_3),使钴的析出电位向正方移动,而且阴极电流增大,因而有可能发生RE(La、Tb、Dy、Tm)与Co的诱导共沉积。在尿素-NaBr-KBr-NaOAc-CoCl_2-RECl_3熔体  相似文献   

4.
FERROMAGNETICINTERACTIONBETWEENGADOLINIUM(Ⅲ)ANDCOPPER(Ⅱ)IONSINN,N'-BIS(2-AMINOPROPYL)OXAMIDOCOPPER(Ⅱ)BRIDGEDBINUCLEARGd(Ⅲ)-Cu...  相似文献   

5.
在乙腈介质中合成了苯并-12-冠-4(简称B-12-C-4)和单环己基-12-冠-4(简称Cy-12-C-4)的六种希土配合物:RE(NO3)3·B-12-C-4(RE=Pr,Gd,Yb,Lu),RE(NO3)3·Cy-12-C-4(RE=La,Lu)。研究了它们的IR及^1HNMR性质,并测定了四种单晶的结构,用INDO法计算了Lu(NO3)3·B-12-C-4,Lu(NO3)3·Cy-12-C  相似文献   

6.
LASER-ENHANCED ELECTROCHEMICAL DOPING OF POLY (N-VINYLCARBAZOLE)LASER-ENHANCEDELECTROCHEMICALDOPINGOFPOLY(N-VINYLCARBAZOLE)Ya...  相似文献   

7.
PREPARATION, ELECTRICAL PROPERTIES AND CRYSTAL STRUCTURE OF TWO NEW CHARGE-TRANSFER SALTS (BEDT-TTF)_3Cu_2Brx AND (TTM-TTF) (...  相似文献   

8.
THEEXCITEDSTATESANDVIBRATIONALFREQUENCIESOFBli:(e=0,+1,-1)CLUSTERSTHEEXCITEDSTATESANDVIBRATIONALFREQUENCIESOFBli:(e=0,+1,-1)C...  相似文献   

9.
ELECTRON-TRANSFERINPOLYNUCLEARCYANO-BRIDGEDCOMPLEXOFTHETYPE[Co(Ⅲ)L_3-μ-Nc-FeⅡ)(CN)_5]~-(L=en)ShuZhongZHAN;XiaoYuanCHEN;QingJin?..  相似文献   

10.
气体法低温稀土多元共渗的研究   总被引:5,自引:1,他引:5  
从自制的多种渗剂中,筛选了含稀土的最佳渗剂,实现了气体法低温稀土、硼、碳、氮、氧多元共渗。获得了组织、性能和层深远优于其它低温化学热处理的渗层。用金相、扫描电镜、光电子能谱和正电子湮没等技术,对渗层进行了较系统的分析,对稀土的催渗等基本理论问题进行了探讨。  相似文献   

11.
In the present work, the plasma nitriding behavior of a nickel based dental alloy was investigated. Plasma nitriding experiments carried out under constant gas mixture (15% H2?C85% N2) for different process parameters including time (4, 6, 10, and 20 h) and temperature (400, 450, 500, and 550 °C). Depending on nitriding parameters, it was found that triple or double layers formed on the surface of the samples. Increasing of treatment time and temperature has resulted in a double layer. ??N1 layer was in formed all nitrided samples. However, ??N2 layer is formed only at low temperatures and in short times. Layer growth of nickel based alloys increases until a critical time or a critical temperature reached. Above these critical values, it is observed that the layer thickness decreases. It was also found that plasma nitriding not only increases the surface hardness but also improves the wear resistance of nickel based dental alloy. The maximum wear resistance was observed at 400 °C for 10 h due to the high hardness and thickness of the nitride layers.  相似文献   

12.
以N2与H2的混合气为反应气,和三氧化钼进行多段程序升温反应,制得一种β晶型的氮化钼。以噻吩为模型化合物的常压加氢脱硫反应表明,β-Mo2N0.78具有较强的加氢脱硫活性和强的抗硫化性能。同时考察了预还原、反应温度以及氮化末温、升温速率、反应气中N2-H2比及氮化时间等制备参数对β-Mo2N0.78加氢脱硫活性的影响。研究发现,β-Mo2N0.78的加氢脱硫活性在320 ℃~400 ℃随反应温度的升高增强,而还原预处理会降低催化剂的活性。氮化末温、氮化时间、反应气组成和升温速率等制备参数对催化剂的活性有明显的影响:随着氮化末温的升高,所制备的催化剂催化加氢脱硫活性降低;在氮化末温恒温较长时间,可以引起制备催化剂的加氢脱硫活性下降;存在最佳的反应气组成和各段升温速率。小晶粒的β-Mo2N0.78具有强的加氢脱硫活性。  相似文献   

13.
W2N/C催化剂加氢脱氮的研究   总被引:1,自引:0,他引:1  
制备了加氢脱氮高活性催化剂W2N/C,探讨了氮化温度对催化剂活性的影响,考察了W2N/C催化剂上吡啶的加氢脱氮规律,提出了在该催化剂上吡啶加氢脱氮反应机理。  相似文献   

14.
Resistance of stainless steels to pitting corrosion is strongly enhanced by nitriding at 380–450°C. In this work, anodic behaviour of steels with 0.13, 2.1, 4.5 and 6.1 wt% Mo was studied before and after nitriding at 450°C for 30 h which gave 13.0–15.8 wt% N at the surface. Electrochemical measurements were carried out in 0.1 M Na2SO4 + 0.4 M NaCl at pH 3.0. Nitriding of steels with lower Mo contents (0.13 and 2.1 wt% Mo) enhanced the resistance to pitting corrosion; steels with higher Mo contents retained their high resistance to pitting but underwent an activation. Nitrogen increased anodic reactivity in initial stages of polarisation, and it also increased the passivation rate. X-ray photoelectron spectroscopy analysis showed that anodic films on nitrided steels contained oxides at the outer surface and Cr–N species deeper from the surface. The enhanced resistance to pitting corrosion of low-temperature nitrided steels is explained by the increased anodic reactivity which leads to the formation of a salt-type film with Cr/Fe oxides and Cr–N species.In Honour of Professor Kurt Schwabe.  相似文献   

15.
This article presents the influence of surface additions of nanocrystalline rare earth (RE) oxides CeO2, La2O3, and CeO2 + La2O3 on the isothermal oxidation behavior of Fe20Cr and Fe20Cr5Al at 1000 °C. Thermogravimetric studies revealed parabolic kinetics in all cases and the scale thickness on specimen surfaces varied with the nature of RE oxide. The oxidation resistance of specimens coated with two RE oxides was significantly higher than those coated with either one of the two oxides. The marked increase in the oxidation resistance of the alloys coated with two RE oxides is due to optimization of RE ion radius and RE oxide grain size/shape.  相似文献   

16.
微合金钢中稀土钒复合作用的研究   总被引:3,自引:2,他引:1  
稀土在钒微合金钢中有一定的固溶量,并可达10^-5-10^-4(质量分数)数量级,稀土降低碳氮化钒完全溶解的温度,阻止奥氏体中钒的应变诱导析出,在铁素体区稀土促进碳氮化钒析出,并细化沉淀相,钒和稀土复合微合金化有更强的推迟形变奥氏体动态再结晶,抑制奥氏体晶粒长大和细化晶粒的作用。  相似文献   

17.
采用主碳当量灰铸铁作为试验材料,以孕育处理的方式加入稀土和氮,研究了稀土,氮及二者复合能对石墨数量和石墨表面形貌的影响。试验结果表明,稀土和氮,特别是它们复合加入,使石墨百分含量减少;氮和氮与稀土复合孕育使灰铸铁的石墨表面变粗糙,且端部有钝化现象。  相似文献   

18.
微合金钢中稀土对沉淀相和性能的影响   总被引:3,自引:5,他引:3  
在Nb(Ti,V)微合金钢中,主要沉淀相分别为Nb(C,N),(Nb,Ti)(C,N)和V(C,N)。稀土降低沉淀相完全溶解的温度,增大奥氏体中沉淀相析出的孕育期,降低析出速率,抑制奥氏体中沉淀相的析出,在铁素体相区,稀土提高沉淀相的析出速率和数量,促进沉淀相的析出,其中稀土对铌沉淀相析出的作用影响最强。锻态钢中,稀土有促进细化球化析出相的作用,随稀土含量增加,沉淀相析出数量增加,但过量稀土,促进作用又减弱,稀土在保持微合金钢强度的情况下,显著改善其冲击韧性,尤其是低温韧性,微合金钢中添加适量稀土可获得更佳的综合性能。  相似文献   

19.
稀土对铬锰氮不锈钢在稀硫酸介质中腐蚀磨损性能的影响   总被引:6,自引:0,他引:6  
研究了稀土对铬锰氮不锈钢的腐蚀性能及腐蚀磨损性能的影响,稀土使各锰氮不锈钢的腐蚀电位正移、维钝电流降低、热力学稳定性提高,故其耐蚀性提高,抗磨性改善,铬锰氮不钢的最佳稀土含量为0.02-0.06%,为生产提供了必要的工艺参数。  相似文献   

20.
The influence of nitriding pretreatments of steel substrates on the adhesion of representative ceramic coatings has been investigated. Vapor phase nitriding using the mixture NH3/H2/He has been applied before the growth by MOCVD of vanadium nitrides, carbonitrides and oxides. Similarly, microwave plasma nitriding using the mixture N2/Ar was applied prior to the deposition by PACVD of silicon carbide based films. The nitriding pretreatment enhances the adhesion of plasma SiC(H) and MOCVD V(C,N) and V2O3 coatings but is not favorable to a better adhesion of MOCVD VN-type films. The different mechanical behaviors of these coatings are discussed in terms of compatibility between the combined processes.  相似文献   

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