Hot-dip Method Research Articles

Influence of Additional Alloying Elements on Corrosion Resistance of Hot Dip Galvanised Steels

The alloying of the zinc with some additional elements in specific quantities could be reliably used in the hot-dip coating process. These elements form specific intermetallic compounds that conferred substantially improved performance to the end-product specially by improving of the corrosion resistance. The paper presents the research that has developed to analyze the influence of aluminum, bismuth and tin like alloying elements added in the zinc on corrosion resistance of galvanized steels. Steel samples were galvanized by the hot-dip method in micro-alloyed zinc baths. The influence of the alloying elements on the formation of the different phases and on the diffusion process is discussed. The corrosion experiments were carried out in a simulated environment of accelerated corrosion conditions. The kinetics and the mechanism of corrosion of the samples were studied in correlation with the effect of alloying elements on nature and characteristics of protective layers.

Preparation Methods of Copper-Steel Composite Wire

The domestic and foreign preparation methods of copper-steel composite wire are introduced in the paper, they are basically plating method, hot-dip plating method, continuous extrusion method, clad-welding method and hot extrusion welding method. The advantages and disadvantages of these methods are compared and analyzed. Among of them, hot extrusion welding method is a common method in foreign for producing copper clad steel wire. In recent years, the equipment and the technology are introduced by domestic companies and put it into production, it fills up the gap for producing copper clad steel wire in the domestic and it provides new market and application prospects for copper clad steel wire produced and applied in the domestic.

The structure of coatings obtained in the Zn-31Al-3Mg bath by the batch hot dip method

Zn-Al dip coatings provide effective protection of steel surface against corrosion - better than traditional zinc coatings. Corrosion resistance can be further increased by adding Mg to the bath. Coatings obtained in Zn-Al-Mg baths are produced on metal plates by applying the continuous method. In this paper the author presents the results of tests on obtaining Zn-Al-Mg coatings on products with limited shape by use of the batch hot dip method. The growth kinetics of coatings obtained in the Zn-31Al-3Mg bath on steel with low silicon contents has been defined. The structure has been developed and the chemical composition of particular structural components of the coating has be established. It has been determined that the structure of coatings obtained in the Zn-31Al-3Mg bath is continuous. The course of reaction between the tested steel and liquid Zn-31Al-3Mg alloy is very abrupt, which leads to the formation of coatings with excess and non-uniform thickness.

Cast joining of cast iron to aluminium casting matrix

The present study focused on reinforcing Al–Si–Cu alloy with a cast iron insert and using Zn–xAl–3Si–0·5Mg (wt-%) intermediate alloys by the cast joining technique to take advantage of lightness and stiffness of the hybrid structure. The experimental set-up consisted of coating the insert using hot dipping method followed by immersing the coated insert into the Al melt and allowing the system to cool down to the room temperature. The quality of Al–Fe joints in terms of morphology, thickness, chemistry and microhardness was evaluated as a function of coating composition and immersion time in the Al melt. Characteristics of reaction layer at the coating/insert interface and its effects on the joint properties were determined using microstructural analysis and thermodynamic calculations. Combination of a suitable coating containing 27 wt-%Al and optimised process parameters, including 1 min immersion time, resulted in the formation of an Al–Fe joint with promising characteristics.

Degradation of Aluminide Layers During Cyclic Oxidation of Ferritic 430 Stainless Steel

In order to increase the performance of the preferred Ferritic 430 SS for manufacturing automobile and motor-cycle exhaust systems. The aluminizing coating on the surface of bare steel was applied by hot-dipping method in a molten pure aluminum. The high temperature oxidation of the aluminized steel was cyclically studied at 900 °C and 1000 °C in static air. The degradation of intermetallic layers during cyclic oxidation were analyzed by means of X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The crack perpendicular to the specimen surface rapidly propagated through the FeAl and Fe3Al layers due to a thermal expansion mismatch upon cooling to room temperature. The accumulation of voids generated crack at the interface between the aluminide layer and the steel substrate. Oxygen is allowed to penetrate into the aluminide layer crack, rapidly forming alumina oxide and closing the crack. Some of the aluminide layers peeled off due to this rapid growth. Thus, the protective Al2O3 layer degraded and later, the substrate was oxidized subsequently to form iron-rich oxide (Fe2O3) at 1000 °C.

Influence of the cooling method on the structure of 55AlZn coatings

In metallization processes, metals or metal alloys are used which have a low melting point and good anticorrosion properties. Moreover, they must form durable intermetallic compounds with iron or its alloys. The most common hot-dip metallization technology involves galvanizing, however, molten multi-component metal alloys are used as well. An addition of aluminium to the zinc bath causes an increase in corrosion resistance of the obtained coatings. The article presents results of tests of obtaining coatings by the batch hot-dip method in an 55AlZn bath. Kinetics of the coating growth in the tested alloys were determined in the changeable conditions of bath temperature, dip time and type of cooling. The structure of coatings and their phase composition were revealed. As a result of the tests performed, it has been found that an increase in total thickness of the coatings as a function of the dipping time at a constant temperature is almost of a parabolic nature, whereas an increase in the transient layer is of a linear nature. The structure was identified by the XRD analysis and the morphology of the coatings was tested by means of SEM. It has been found that the cooling process with the use of higher rates of cooling causes a size reduction of the structure in the outer layer and a reduction of thickness of both the intermediate diffusion layer and the whole coating by ca. 25 %.

Analysis and self-lubricating treatment of porous anodic alumina film formed in a compound solution

A porous anodic film on aluminum was prepared in a mixed electrolyte of phosphoric acid and organic acid and cerium salt, and ultrasonic impregnation technology was applied on it to form self-lubricating surface composite. The structure and chemical composition of the film and its lubricity after self-lubricating treatment were investigated in detail. EPMA indicates the cross-section of anodized film has two distinct oxide layers. Al, O and P are found in the film with different distribution in the two layers. XPS analysis on the electron binding energy of the component elements show the chemical composition of film surface are Al 2O 3, Ce(OH) and some phosphates. The structure of anodized film is amorphous with XRD analysis. The tribological tests shows the frictional coefficient of the self-lubricating surface composite coating is 0.25, much lower than anodized aluminum and aluminum substrate, which is about 0.55 and 0.85, respectively, and it is also durable for a long period of time in comparison with the lubricating coating fabricated by hot-dipping method. SEM images show some PTFE particles are added into the nanoholes of anodic oxide film.

Influence of alloying elements on the structure and corrosion resistance of galvanized coatings

61.10.Nz, 68.35.Fx, 68.37.Hk, 81.15.–z, 81.65.Kn Carbon steel samples were galvanized by the hot-dip method in zinc baths containing 0.5 or 1 wt% alumi-num, copper, tin, nickel, and/or lead. Bath temperature ranged from 450 to 480 °C. The samples were examined using optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influence of the alloying elements on the formation of the different phases and on the diffusion pro-cess is discussed. In order to study the kinetics and the mechanism of corrosion of these materials, corro-sion experiments were carried out in a simulated environment of accelerated atmospheric corrosion condi-tions, for which a special chamber (Salt Spray Chamber – Alternative Climate Test Chamber) of type SC-450 was used. The corroded samples were examined using optical microscopy, SEM and XRD. Chloride and oxide phases, which penetrated the materials to different depths from the surface, were revealed. Fi-nally, useful conclusions were drawn which help to control the factors of the corrosion behavior of the examined materials in a marine atmosphere.

Hot-dip method and device for zinc plating

Hot-dip method and device for zinc plating

溶銅浸せき法による銅覆鋼線の開発と応用

溶銅浸せき法による銅覆鋼線の開発と応用

各種金属材料および防錆被覆の大気腐食に関する研究 (第6報)

In this report, results obtained from weathering test on metallic coatings for 5 years (started in April, 1960) were summarized.The tests were conducted at the 7 sites mentioned in the 1st report; they were selected as typical representatives of different environments, e. g., industrial, seaside, and inland.The specimens were made from mild steel plates, and metal-coated by electroplating, metallizing or hot-dipping. They were exposed to the atmosphere, and their corrosion resistivities affected by the environmental peculiarities were compared.Results obtained were as follows:(1) For rust-proof, metallic coatings by aluminum and by zinc were equally effective regardless of the method of coating.(2) In metallic coating methods, hot-dipping method was the most effective, followed by metallizing and then electroplating.(3) For consumption and rusting of the metallic coating, the atmospheric pollution was seen to be more responsible than the meteorological factors.

アルミナイズド鋼の基礎的研究（第1報）

When aluminized steel is prepared by hot-dipping method, an alloying layer will be formed on steel in varying thickness from 1.5∼2.5×10−2 mm, consisting of an outer layer of relatively pure aluminium and an inner layer of iron-aluminium compound. The lower the temperature of immersion, the thicker is the pure aluminium and the longer the time of immersion at any temperature, the thicker is the alloying layer. The controlling of this layer has important effect on the various properties of aluminized steel. In the present experiment, the effect of carbon content in steel and of the composition of the aluminium bath on the alloying action between steel and melted aluminium is determined continuously by means of the apparatus as shown in Fig. 1. The results obtained are as follows: (1) By an increase of carbon content in steel, the growth of the alloying layer is restrained markedly. (2) The growth of the alloying layer is not restrained by the addition of 0.1 and 0.4% of Ti, but an addition of 1.0%Ti is effective in preventing the grow of the alloying layer.