An Du

Influences of Si on corrosion of Fe–B alloy in liquid zinc

Abstract Influences of silicon content on the microstructure and corrosion resistance of a Fe–2·5 wt-%B alloy have been investigated by using scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. Si can change the microstructure from hypereutectic to eutectic and furthermore, enhance the corrosion resistance of the alloy in molten zinc. The high corrosion resistance of the alloy was mainly attributed to the eutectic phase increase and solubility of Si in α phase enhancement. The corrosion of these alloys in liquid zinc was controlled by the diffusion mechanism. The reaction products are FeZn6·67, Fe5SiB2 and FeSi. The reaction layer further prevents the diffusion of zinc atoms into the base material and delays the reaction between the substrate and the molten zinc efficiently.

Effect of Si addition on the stability of Al-10Ti-5Cu-xSi alloy/SiC interface

Abstract The effect of Si addition on the interfacial stability of Al-10Ti-5Cu-xSi (x = 0, 5, 10, 15) alloy/SiC is investigated. SiC and the Al-10Ti-5Cu-xSi alloys were compacted to obtain a stable interface with 10 wt% Si. Analysis of the processing conditions and the microstructures indicated that an excellent Ti3SiC2 phase had been formed and the deleterious Al4C3 phase had been eliminated successfully by the addition of 10 wt% Si to the Al-10Ti-5Cu alloy. Formation of Ti3SiC2 increased at first and then decreased, while the formation of Al4C3 was gradually inhibited with increasing Si content. Ti3SiC2 possesses good chemical stability, and flexibility. However, Al4C3 degrades within few days, in composites exposed to ambient conditions. The presence of Ti3SiC2 at the interface and the elimination of Al4C3 together ameliorate the bonding of Al-10Ti-5Cu-xSi alloy to SiC, thereby improving the interfacial stability of Al-10Ti-5Cu-xSi/SiC.

Corrosion behaviour of stoichiometric Fe3Si alloy in liquid zinc

Abstract The corrosion behaviour of stoichiometric Fe3Si alloy in a liquid zinc bath for 3 and 62 h at 500°C was examined. The corrosion products at the Fe3Si/liquid zinc interface were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The corrosion process was controlled by the diffusion of iron and zinc atoms. There were scarcely any silicon atoms diffusing at Fe3Si/liquid zinc interface from the matrix to liquid zinc. The phase transition process of the stoichiometric Fe3Si alloy in liquid zinc was Fe3Si, α, α+ FeSi+δ, FeSi+δ, and the main corrosion products were periodic array of FeSi and δ phase.

Metal/Ceramic Laminar Composite Immersion Heater for Heating Hot Dip Galvanizing Zinc Kettle

A new type of laminar composite material has been developed by the bonding of ceramic and metal with a special agglutinate metal. A tube can be made of the laminar composite material and this tube can perform as an outer sheath of an immersion heater. Such heaters can be made to lager size and can be heated using a wide range of energy sources including electricity, gas and oil. Moreover this new heater tube is low cost and has a long working life, is convenient to use and requires little maintenance. This technology allows all kinds of zinc kettle to be heated by immersion heaters.

Study of Process of Hot-Dipped Galfan Coating on Q235 Structural Steel

A different production method including a formulated flux has been devised to hot-dip Q235 Galfan alloy coating on structural steel. The microstructure and composition of the Galfan coatings, applied by the hot dip process, was performed using SEM and EDS technology to evaluate the coating thickness and its relationship with technological parameters. The experimental results showed that the coating of specimen has eutectic crystal shape and its thickness is thinner than Zinc coatings’ scale. Moreover, the Galfan plating does not grow with the extension of time for immersion. The temperature of immersion and the extraction speed will affect the coating thickness too.

Spot Welding Quality Prediction Model Based on Partial Least-Squares Regression

The relationship between spot welding process parameters and nugget diameter was selected and synthesized by partial least squares. The partial least squares regression model of spot welding quality was established. And the nugget diameter was predicted based on the model mentioned above. The results show that this model can be used to predict the spot welding quality.

Effect of Rare Earth Salt on Ceramic Membrane Formed by Micro-Arc Oxidation

TiO2 layers were fabricated via micro-arc oxidation process in the electrolyte of adding rare earth and in original electrolyte solution respectively .The ceramic membrane and the change of voltage were analysed.The results indicated, the ceramic membrane were formed faster in electrolyte solution of addingrare earth. Surface morphology and voltage changed obviously by adding rare earth salt. The optimal concentration of ceric sulfate and lanthanum nitrate were 0.018 mol /L and 0.046 mol /L respectively.

The Study of Technics Behaviors of Micro-Arc Oxidation on Al-Ti Alloys

In this paper, surface morphology and phase constitution of ceramic membrane fabricated via Micro-arc oxidation on Al -Ti alloys was studied .The via Micro-arc oxidation was reacted in phosphate and silicate mixed electrolyte.And by contrasting of phase constitution of the ceramic membrane, the relationships of thickness of the ceramic membrane and time,and the relationships of arcing voltage and time to inquire the features of Micro-arc oxidation on Al -Ti alloys.

Corrosive Wear Behavior of Several Materials Coupled with Si3N4 in the Molten Zinc

In continuous hot dip galvanizing, serving parts working in the molten zinc, such as sink roll, sleeves, etc. tend towards degradation and failure due to corrosion and wear. In this paper, corrosive wear performance of several materials, such as boronized，H13，Co-based alloy and Fe-based alloy coupled with Si3N4 is evaluated with the aid of a self-made test machine of block-column sliding wear. Moreover, the corrosive wear mechanism is analyzed. It has been found that these materials suffered not only considerable wear, but also the corrosion of molten zinc. For boronized layer, the wear is the main reason to cause the failure of work parts under the act of the corrosive wear. For H13, the interaction between corrosion and wear plays a very important role on its failure. For those alloys with bad corrosion resistance such as Co-based alloy and Fe-based alloy, both corrosion of solid solution and wear of intermetallic compound act on their failure at the same time. However, the rate of wear shows no obvious relation to the hardness although wear performance is important. The failure greatly lies on the ratio of the hardness of corrosion products to matrix.

Baysesian Neural Network Approach to Detecting Temper Embrittlement of 30Cr2MoV Rotor Steels

Baysesian Neural Network approach for predicting the temper embrittlement of steam turbine rotor in service was proposed. The FATT50 (the fracture appearance transition temperature) of the rotors was predicted as a function of ratio of the two peak current densities (Ipr / Ip ) tested by electrochemical potentiodynamic reaction method, temperature of electrolyte, J-factor and grain size ( N ). A database was obtained from the test of electrochemical potentiodynamic reaction and Charpy impact. The Bayesian neural network technique was used for modeling of temper embrittlement. The neural network shows a more precise prediction of temper embrittlement of rotor steels than the prediction using multiple linear regression. The training error and verifying error is with the scatter of ±20°C. The results show that, for the temper embrittlement of rotor steels prediction, the prediction model based on Bayesian neural network is feasible and effective.