Papers by Keyword: Hot Dip Galvanizing

Abstract: This study aims to find material steel for animal feed chopper machine which is not easily corroded with method of hot dip galvanizing (HDG). Steel as machinery components or construction often gets broken before the predicted time because of corrosion. The HDG method was begun by pre-treatment process which were polishing, degreasing, rinsing I, pickling, rinsing II, fluxing, and drying. The main process of galvanizing was done by dipping in 98% of zinc solution with temperature variation of 430, 450, 470, and 490°C. The coating thickness measurement was run with Coating thickness NOVOTEST TP-1M. The corrosion was tested with electrochemical method of potentiodynamic polarization with AUTOLAB PGSTAT 128. The highest value of coating thickness was at galvanized temperature of 490°C which was 88.9 ± 3.24%. The value of standard deviation was indicated by how much the coating homogeneity formed. This was in line with the amount of corrosion rate at galvanized temperature of 490°C. The highest corrosion rate values in H₂SO₄ and NaCl environment were 1.18 and 0.21 mm/year. The highest hardness value of Zn layer is galvanizing temperature of 490°C which rises 41.71% of the base metal. The coating thickness, corrosion and surface hardness test have thee good agreement.

Abstract: The article contains the findings on impact of zinc coating specifications on corrosion resistance and service life of steels of various chemical composition used often in modern industries. Characteristics such as type, class, chemical compound and thickness of zinc-based coatings are also addressed. Experiments were performed in which corrosion rate and useful life of zinc coatings in probable operating-like conditions — i.e., in environments of varying degrees of corrosive power (humid and high-chloride environments) were determined. It has been established which one of the environments is the most corrosive for steels depending on the zinc-based coatings’ specifications. Qualitative (visual) and quantitative (gravimetric) assessment of corrosion resistance and service life of chosen steels is presented. Optimal hot dip galvanized coating specifications were determined using statistical analysis.

Abstract: Corrosion rate of hot dip zinc coating exposed at atmospheric environment can be predicted according to EN ISO 9223 and EN ISO 9224. Prediction models based on dose response (D/R) functions express the effects of environmental parameters on the corrosion of material. The investigation of corrosion protection of construction exposed longer than 30 years were performed. In this paper the selected results of evaluation of galvanised infrastructures from corrosion failure and durability point of view are presented. The field data are compared to prediction models. The residual thickness of zinc coating was measured on selected profiles of the truss structures. The maintained organic coatings were applied on these constructions and there are presented results after 8 years.

Abstract: 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.

Abstract: 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.

Abstract: In the paper the results of tests on obtaining zinc coatings on reinforcing steel are presented. The coatings were obtained in a zinc bath on B500SP rebars of various diameters. The structure of coatings obtained on rebars with the diameter of 12, 16, 20 and 32 mm has been developed. The chemical composition of structural components of the coating has been established. The growth kinetics of coatings obtained in the traditional galvanizing process at the temperature of 450°C has been established and the impact of the rebar diameter upon the coating growth curve has been defined. The obtained coatings are continuous and they are quite thick. Moreover, it has been determined that an increase in the rebar thickness induces an increase in the coating thickness.

Abstract: In the paper the results of tests conducted to determine the synergistic influence of alloy additions to a zinc bath upon the structure and growth kinetics of coatings obtained on reinforcing steel are presented. The structure and the chemical composition of coatings obtained on B500SP steel have been developed. The tests were carried out in Zn-AlNi, Zn-AlNiBi and Zn-AlNiBiSn baths. It has been determined that the additions of Bi and Sn reduce the coating thickness on B500SP reinforcing steel. The growth kinetics of coatings on the tested reinforcing steel - even though the concentration of Si was within the Sebisty range - did not show reversed temperature dependence, which is characteristic of this type of steel.

Abstract: 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.

Abstract: 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.

Abstract: Steel constructions are an integral part of our lives, surrounding us almost everywhere. They are used for erection of various halls, bridge structures, railings etc. Each steelwork is more or less impaired by corrosion, respectively a certain level of corrosion aggressiveness of the environment. Corrosion is the cause of material degradation - referred to rusting. In order to avoid this unwanted phenomenon to the maximum extent possible, we use various methods and technologies protecting the relevant material and preventing from corrosion occurrence and development. This article deals with one of the methods aimed at corrosion protection of structural steelwork - duplex coating system that is assured by means of hot dip galvanizing followed by paint system application.