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In the hot dip galvanizing process two different fluxes are used to remove the zinc oxide layer, always present on the liquid zinc surface. When this oxide layer, which contains also aluminium oxide, is dragged into the zinc by the articles, interfering the reaction zinc‐iron. In former days a flux floating on a part of the liquid zinc surface was rather common, at present this wet flux is almost completely replaced by the dry galvanizing process. Since the chemical reactions taking place in the wet flux, partly take place in the flux for dry galvanizing too, first this wet flux will be discussed in brief.

Zinc coatings are applied commercially by hot‐dipping, electro‐deposition, metal‐spraying, cementation and vacuum deposition (see Table 5). Galvanizing (zinc hot‐dipping) has been done for more than 200 years now and is undoubtedly the most widely‐used form of metal coating. The production and pro‐perties of these coatings have received intensive study over the last 10 years; much of this has been reported at the ‘International Conferences on Hot‐Dip Galvanizing’.

The author describes some of the developments in the increasing use of zinc‐coated steel, which in one form or another is used in most industries. Emphasis is given to galvanizing, which is by far the most important coating process.

Recently, several studies have been performed on lap welding of aluminum and copper using friction stir welding (FSW). The formation of intermetallic compounds at the weld interface hampers the weld quality. The use of an intermediate layer of a compatible material during welding reduces the formation of intermetallic compounds. The purpose of this paper is to optimize the FSW process parameters for AA6063-ETP copper weld, using a compatible zinc intermediate filler metal.

In the present study, a three-level, three-factor central composite design (CCD) has been used to determine the effect of various process parameters, namely, tool rotational speed, tool traverse speed and thickness of inter-filler zinc foil on ultimate tensile strength of the weld. A total of 60 experimental data were fitted in the CCD. The experiments were performed with tool rotational speeds of 1,000, 1,200 and 1,400 rpm each of them with tool traverse speeds of 5, 10 and 15 mm/min. A zinc inter-filler foil of 0.2 and 0.4 mm was also used. The macrograph of the weld surface under different process parameters and the tensile strength of the weld have been investigated.

The feasibility of joining 3 mm thick AA6063-ETP copper using zinc inter-filler is established. The regression analysis showed a good fit of the experimental data to the second-order polynomial model with a coefficient of determination (R²) value of 0.9759 and model F-value of 240.33. A good agreement between the prediction model and experimental findings validates the reliability of the developed model. The tool rotational speed, tool traverse speed and thickness of inter-filler zinc foil significantly affected the tensile strength of the weld. The optimal conditions found for the weld were, rotational speed of 1,212.83 rpm and traverse speed of 9.63 mm/min and zinc foil thickness is 0.157 mm; by using optimized values, ultimate tensile strength of 122.87 MPa was achieved, from the desirability function.

Aluminium and copper sheets could be joined feasibly using a zinc inter-filler. The maximum tensile strength of joints formed by inter-filler (122.87 MPa) was significantly better as compared to those without using inter-filler (83.78 MPa). The optimum process parameters to achieve maximum tensile strength were found by CCD.

This paper aims to investigate the composition of lubricant and the enhancement of tribological properties using palm oil as a parent base oil mixed with an organo-zinc compound as an additive.

The oil samples were prepared by mixing organo-zinc compound additive, zinc dioctyldithiophosphate (ZnDoDP) and zinc diamyldithiocarbamate (ZDDC), at 0 to 3.0 Wt.% concentrations with commercialised palm oil which were then homogenised using an ultrasonic homogeniser. The oil samples were then tested for their oil properties through elemental analysis, their viscosity index, flashpoint and acid number. Next, the friction test was performed using a four-ball tribometer, and the worn surfaces of the balls were observed using a digital microscope.

The results showed that commercialised palm oil with 2.0 Wt.% of ZnDoDP had excellent characteristics regarding its lubricant properties, such as its viscosity index, coefficient of friction and wear compared to commercialised palm oil with the addition of 2.0 Wt.% of ZDDC.

To the best of the authors’ knowledge, this is the first study to compare the effect of the concentration of ZnDoDP and ZDDC on the lubricant and triological properties of vegetable oil (palm).

Introduction Zinc weight per unit area is a crucial factor in the durability of galvanised parts with respect to corrosion and may be correlated with the thickness of the galvanised coating by means of the latter's density. Thus, the thicker the coating, the longer the part is bound to last.

Introduction Most methods of protection of steel involve putting an extra layer of some corrosion resistant material between the steel and the environment. The main action of paints and plastics, for example, is to prevent contact between the atmosphere and the steel. However if there is damage to such a protective film, corrosion occurs at the break and spreads outwards lifting and destroying the film as it goes. Similar effects can also occur from the inherent pores in paint films.

A report on the quality of the galvanised coating applied to Swedish electricity power pylons some 23 years ago, including details of an interim examination made after 15 years exposure.

This study aims to enhance to corrosion protection of NiZn-plated steel by electroplating multilayer coating.

The multilayer coating consists of three layers on mild steel substrate, such as Cr³⁺ chromate conversion layer (CCC), electrodeposited nanosilica zinc-nickel composite layer (ZnNiSi) and electrodeposited zinc-nickel alloy layer (ZnNi). Its morphology, composition and corrosion behaviour were investigated by various methods.

Polarization curves indicated that polarization resistance and corrosion current density of CCC/ZnNiSi/ZnNi/Fe (6.956 kO.cm2; 2.56 µA.cm⁻²) were two times higher and five times lower than that of ZnNiSi/ZnNi/Fe (3.42 kO.cm²; 12.52 µA.cm⁻²), respectively. From electrochemical impedance spectroscopy data, charge transfer resistances were 1.344, 2.550 and 2.312 kO.cm² for ZnNi, ZnNiSi/ZnNi and CCC/ZnNiSi/ZnNi, respectively. Salt spray test indicated that after 48 h, surface of ZnNi and ZnNiSi was covered by white rust, whereas no white rust was observed on surface of CCC/ZnNiSi/ZnNi. After 600 h, there were red rust spots (1% surface coverage) on surface of Zn-Ni, whereas only white rust was observed on both ZnNiSi/ZnNi (100% surface coverage) and CCC/ZnNiSi/ZnNi (10% surface coverage).

Multilayer coating enhanced significantly the corrosion protection for steel, as compared to the single-layer coating.

Ongoing reductions in dielectric thickness for metallized AC capacitors, has resulted in a shift away from pure aluminium coatings for capacitor materials to be used in higher voltage applications. Metallized electrodes such as zinc with silver prenucleation, zinc/aluminium composites and aluminium bilayers are now required for AC capacitors. This paper will discuss the design aspects of a vacuum web coater to provide this wider range of requirements.