H. Kania

Synergistic influence of Al, Ni, Bi and Sn addition to a zinc bath upon growth kinetics and the structure of coatings

In this article the authors have analysed the current knowledge about the influence of alloy additions used in galvanizing baths. The optimum concentration of Al, Ni, Bi and Sn addition has been established. Some tests have been conducted to determine the synergistic effect of the addition of AlNiBiSn to a zinc bath upon the structure and growth kinetics of coatings. The structure of the coatings obtained on steel with low silicon contents and on Sandelin steel as well as their chemical composition have been revealed. It has been established that the addition of AlNiBiSn helps to reduce excessive growth of coating on Sandelin steel. The chemical composition and the structure of the coating on Sandelin steel are similar to the chemical composition and structure obtained on steel with regular silicon contents.

The Influence of the Chemical Composition of a Zinc Bath upon Corrosion Resistance of Coatings Obtained on Sebisty Steel

In the paper the results of tests defining the influence of the chemical composition of a zinc bath on the corrosion resistance of coatings obtained on Sebisty steel are presented. The coatings for the tests were produced on Sebisty steel with the content of silicon of 0.18 wt. % in Zn-AlNi, Zn-AlNiPb and Zn-AlNiBiSn baths. Corrosion resistance of coatings obtained in alloy baths was compared with the corrosion resistance of a coating obtained in a bath of pure Zn. The structure of coatings has been developed, the chemical composition of structural components of the coating and the coating thickness have be established. Corrosion resistance of the coatings was defined by comparative methods in a standard corrosion test in neutral salt spray. The tests were carried out in accordance with the EN ISO 9227 standard. It has been established that alloy additions to a zinc bath have impact upon corrosion resistance of obtained coatings. The addition of Pb results in a decrease in corrosion resistance of a coating obtained on Sebisty steel.

Synergistic Influence of the Addition of Al, Ni and Pb to a Zinc Bath upon Growth Kinetics and Structure of Coatings

In this paper the current knowledge about the influence of alloy additions used in galvanizing baths has been analysed. The optimum concentration of Al, Ni and Pb addition has been established. Tests have been conducted to determine the synergistic influence of the addition of AlNiPb in a zinc bath upon the structure and growth kinetics of coatings. The structure and the chemical composition of coatings obtained on steel with low silicon contents and on Sandelin steel have been developed. It has been determined that the synergistic influence of the AlNiPb addition effectively lowers the reactivity of Sandelin steel and it improves zincs flowing off the product surface which results in decreased zinc consumption and better appearance of the coating. The structure of coatings obtained in a Zn-AlNiPb bath on Sandelin steel is similar to the structure of coatings obtained on low-silicon steel.

The structure and growth kinetics of zinc coatings on link chains produced of the 23MnNiCrMo5-2 steel

In the paper the results of tests on obtaining zinc coatings on chains produced of the 23MnNiCrMo5-2 steel of grades C and PW9 have been presented. The growth kinetics of coatings obtained in the traditional galvanizing process at the temperature of 450°C has been established. The structure of coatings obtained on chains of various grades has been developed. The chemical composition of structural components of the coating has be established. It has been determined that the obtained coatings are continuous and they are quite thick. No significant impact of the chain grade upon the structure of coating has been established, however, it has been observed that the thickness of coating slightly decreases as the grade increases.

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.

Influence of Hot-Dip Galvanised Coating Morphology on the Adhesion of Organic Coatings Depending on the Zinc Bath Pb Content and the Postgalvanising Cooling Method

Hot-dip galvanised coatings used either alone or with an organic coating (duplex system) constitute an effective anticorrosion protection. Adhesion between the coating and the zinc substrate plays a vital role in the durability of the duplex system. Conditions of the galvanising process and alloying additives incorporated into the zinc bath influence mechanical and protective properties as well as thickness, structure, and surface morphology of the zinc coatings. The influence of the surface morphology of zinc coatings on the adhesion of organic coatings was studied. The tests were carried out on zinc coatings produced in baths with varying Pb content and by employing various cooling methods after the galvanising process. It was noted that a rapid cooling in water produces zinc coatings with a fine-grain structure, more suitable for paint application compared to the air-cooled ones, with a spangle.

The Impact of Al Addition to a Zn-Al Bath upon Growth Kinetics and Structure of Coatings Obtained in the Batch Double Hot Dip Process

In the paper the results of tests on obtaining coatings by use of double hot dip in Zn-Al baths with various Al contents are presented. The coatings were produced in ZnAl baths with the following Al contents: 7, 15, 23, 31 % wt. Al. Based on Zn-Al alloy solidification curves the optimum temperature of the metallization process has been determined. The growth kinetics has been defined and the structure of coatings has been developed. It has been established that an increase in Al contents to 23 and 31% in the bath leads to excessive growth of the coating thickness and its porosity. Smaller contents of Al (7 and 15 % wt.) in the bath allow to obtain coatings of a favourable structure and correct thickness.

Corrosion Resistance of ZnAlMg Alloys for Batch Hot Dip Galvanizing

In the paper the results of corrosion resistance tests on ZnAlMg alloys used as batch hot dip galvanizing baths are presented. The tests were carried out on ZnAl alloys with 7 wt.% Al with the addition of 3 wt.% and 6 wt.% Mg. Corrosion resistance of tested alloys was compared with corrosion resistance of the traditional zinc bath alloy. Corrosion resistance of the alloys was defined by comparative methods in two standard corrosion tests in neutral salt spray and in moist atmosphere containing SO2. Electrochemical parameters of the corrosion process were determined on the basis of potentiodynamic tests. It was determined that the alloy of ZnAl7 has better corrosion resistance than the corrosion resistance of the alloy of a traditional zinc bath and that the addition of Mg to the alloy increases the corrosion resistance.

The Properties of ZnAlMg Alloys for Batch Hot Dip Metallization

In the paper the melting point of Zn-Al alloys with the addition of Mg has been determined, based on solidification curves. The alloys used for the tests were alloys containing 7, 15, 23 and 31 wt.% Al with the addition of 3 or 6 wt.% Mg. It has been determined that the solidification temperature of the ZnAlMg alloy is a synergistic effect of the Al and Mg contents. In alloys with lower contents of Al (7, 15 wt.% Al) an increase in the content of Mg leads to an increase of the melting point. In baths with higher contents of Al (23, 31 wt.% Al) the addition of Mg causes a decrease of the melting point. It has been determined that the melting point of the Zn-31Al6Mg alloy drops to 438°C, due to which the alloy can be used for metallization in temperature conditions close to the temperature of traditional hot dip galvanizing.

The Influence of Si Content in Steel on Growth Kinetics and Structure of Hot Dip ZnAl23Si Coatings

In the paper the results of tests on obtaining coatings in a ZnAl bath of eutoctoid composition on steel with various contents of silicon by use of the batch hot dip method are presented. The growth kinetics of coatings obtained in a ZnAl23 bath with the addition of 1% and 2% of Si on steel with low silicon content (0.01% Si), on Sandelin steel (0.035% Si) and on high-silicon steel (0.27% Si) have been defined. The structure of coatings on tested steels was developed. It has been established that coatings obtained on the Sandelin steel and on high-silicon steel have similar thickness and structure as compared to coatings obtained on low-silicon steel.