Pd-Ni-Al涂层的高温长期氧化行为

利用TGA，XRD，SEM／EDS等方法，研究了Pd改性铝化物涂层在900—1100℃的长期高温氧化行为．结果表明，在900-1100℃下，与简单铝化物涂层相比，β-(Ni，Pd)Al涂层具有较好的抗高温氧化性能．添加改性元素Pd加速了涂层表面的θ-Al2O3向α—Al2O3转变，有利于形成致密的保护膜；另外，Pd还促进了合金基体中Ti元素向涂层的表面以及氧化膜中扩散．     

Pd-Ni-Al涂层的抗高温循环氧化性能

在IN738镍基高温合金上，采用低压固体粉末包埋渗铝方法制备钯改性铝化物涂层。利用TGA、XRD、SEM以及金相等方法，研究了Pd-Ni-Al涂层在1050℃的高温氧化行为。结果表明：与NiAl涂层相比，Pd-Ni-Al涂层表面氧化膜粘附性优良，改性涂层的退化相γ'远少于普通NiAl涂层，显示出优良的高温稳定性。添加改性元素Pd，提高了铝化物涂层的抗循环氧化性能。     

(Ni,Pd)Al涂层的高温热腐蚀

利用XRD，TGA，SEM／EDS等方法，研究了(Ni，Pd)Al涂层在纯Na2SO4以及Na2SO4 25％NaCl两种熔盐环境中的高温抗热腐蚀行为．结果表明，与NiAl涂层相比，(Ni，Pd)A1涂层900℃下具有较好的抗高温热腐蚀性能．添加改性元素Pd，阻碍了S进一步向涂层内层扩散，提高了铝化物涂层的抗高温腐蚀性能．     

Pt改性镍基高温合金铝化物涂层研究进展

综述了镍基高温合金上抗高温氧化的Pt改性β-(Ni,Pt)Al涂层和γ-γ′型涂层,重点介绍了Pt改性铝化物涂层制备工艺,不同工艺条件下涂层的微观结构,Pt增强铝化物涂层抗氧化性能的作用机理,Al对涂层高温氧化性能的影响,并从元素互扩散、相变、表面起伏等方面描述了涂层退化过程,最后对Pt改性铝化物涂层发展进行展望。     

四种典型高温防护涂层的抗氧化性能

目的系统地评价典型高温防护涂层的抗高温氧化性能,并分析其失效机制。方法通过对比普通Ni Al涂层、NiCrAlY涂层、Pt改性Ni Al涂层以及Pt+Hf共改性Ni Al涂层等四种典型高温防护涂层在1100℃的恒温氧化行为,从氧化过程中的氧化增重、组织结构演变规律等角度出发,分析了四种涂层在高温氧化过程中的抗氧化性能以及氧化失效规律。结果四种涂层在1100℃恒温氧化过程中的增重均符合抛物线规律。普通Ni Al涂层氧化膜粘附性能较差,氧化膜快速剥落,涂层退化最快。NiCrAlY涂层中Y元素在氧化膜/涂层界面形成"钉扎"作用,显著提高氧化膜的粘附性能,但由于涂层内部Al元素含量降低,涂层1100℃氧化300 h后基本失效。Pt改性Ni Al涂层的氧化膜较为完整,但氧化膜起伏严重。Pt+Hf共改性Ni Al涂层的氧化膜均匀完整且无明显起伏,具有综合最优的抗高温氧化性能。结论四种涂层的抗高温氧化性能排序为:Pt+Hf共改性Ni Al Pt改性NiAl普通Ni AlNiCrAlY。     

Pt/Zr共改性铝化物涂层的抗高温氧化性能研究

采用电镀Pt和化学气相沉积Al-Zr共渗两步法制备了一种Pt/Zr共改性铝化物涂层,并对其进行了组织结构表征和1000℃抗高温氧化性能测试。结果表明:Pt/Zr共改性铝化物涂层外层主要相为β-(Ni,Pt)Al,同时含有少量的PtAl_2和PtZr相。在1000℃氧化300 h后,Pt改性铝化物涂层和Pt/Zr共改性铝化物涂层中均有大量的有益相β-NiAl存在,表现出很好的抗高温氧化性能;Pt/Zr共改性铝化物涂层比单一的Pt改性铝化物涂层具有更低的氧化速率,其表面氧化膜也更加致密,这是因为在保护性的Al2O3膜下方形成了条状的富Zr氧化物,可以起到钉扎的作用。     

高温合金Al-Si涂层抗高温氧化性能的研究

采用热扩散的方法 ,在K4 38高温合金表面制备了Al Si涂层。经 10 0 0℃× 5 0 0h高温氧化性能试验结果表明 ,K4 38镍基高温合金表面的涂层 ,在高温氧化过程中已转变成致密完整的α Al2 O3氧化层和富铝的 β NiAl和富镍的β NiAl化合物层 ,与基体金属的粘附性良好。Al Si涂层中Si元素的扩散和合理分布能有效的抑制β相的生长 ,延长涂层的退化速度 ,使涂层获得更佳的抗高温氧化性     

(Ni,Pd)Al涂层的高温氧化

在M38镍基高温合金上电镀Pd—20mass％Ni合金，采用低压固体粉末包埋渗铝方法制备钯改性铝化物涂层。XRD分析表明，涂层主要由β—(Ni，Pd)Al相组成。利用TGA、SEM等方法，研究了涂层在800℃～l100℃的初期高温氧化行为。结果表明，800℃、900℃和l100℃下，氧化动力学遵循抛物线规律，1000℃则不是；在800℃和900℃中等温度下，(Ni，Pd)Al涂层表面氧化产物除θ—Al2O3和α—Al2O3外，还含有少量的γ—Al2O3；在1000℃下，涂层表面存在θ—Al2O3和α—Al2O3两种氧化物；在l100℃下，涂层表面氧化产物主要是α--Al2O3。另外，在各温度下涂层表面的氧化产物中都含有少量的TiO2，并且随着温度升高，含量增加.     

Pd-Ni-Al涂层的高温短期氧化行为

在M38镍基高温合金上电镀Pd-20 mass%Ni合金，采用低压固体粉末包埋渗铝方法制备钯改性铝化物涂层，XRD分析表明，涂层主要由β-(Ni,Pd)Al相组成.利用TGA、SEM等方法，研究了涂层在800℃、900℃和1100℃的高温氧化行为表明，β-(Ni,Pd)Al涂层恒温氧化动力学遵循抛物线规律；1000℃氧化动力学则不遵循抛物线规律.在800℃和900℃下，β-(Ni,Pd)Al 涂层表面氧化产物包括α-Al2O3、θ-Al2O3和少量的γ-Al2O3；在1000℃下，涂层表面存在α-Al2O3和θ-Al2O3两种氧化物；在1100℃下，涂层表面氧化产物主要是α-Al2O3.此外，在各温度下涂层表面的氧化产物中都含有少量的TiO2，随着温度升高，其含量增加.     

镍基高温合金上Co改性铝化物涂层的组织结构与耐蚀性能

为研究Co改性铝化物涂层在室温环境中的耐蚀性,利用包埋法渗Co和气相沉积渗Al(两步法)制备出两种不同Co含量的Co改性铝化物涂层,采用XRD、SEM、EDS分析涂层的组织结构。结果表明:850℃和1 000℃渗Co涂层外层和内层均为γ-(Ni,Co)相,内层有氮化物/碳化物相析出。Co改性铝化物涂层与简单NiAl涂层结构一致,外层为β-(Co,Ni)Al相,内层为互扩散区含有大量的富Cr(W)相。简单NiAl涂层的自腐蚀电流为0.04μA/cm2,约为Co改性铝化物涂层的十分之一。这说明在涂层中添加Co降低涂层的耐蚀性,一方面因为Co的腐蚀电位(-0.28V)低于Ni的腐蚀电位(-0.25V),另一方面因为渗Co过程中产生的夹杂物与涂层电位不一致,容易成为微阴极区,加速涂层的腐蚀。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.