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This paper presents, chemistry, test data and processing procedures on a non toxic and environmentally friendly chrome-free conversion coating alternative with the same level of adhesion and secondary corrosion resistance as that found in chrome containing conversion coating systems. Test data from military and independent sources will be presented on secondary coating adhesion, electrical conductivity, filiform and neutral salt-spray corrosion resistance as compared to chromate based systems .on magnesium, aluminum and zinc and their respective alloys. The European “RoSH” initiative will not allow for the presence of any hexavalent chromium on imported electrical components as of July first of 2006. Trivalent chromium based systems generate hexavalent chromium due to the oxidation of the trivalent chromium and as such will not be allowed.

Nisshin Steel Co., Ltd. has developed a new process for the production of a “one-side aluminized steel sheet”. The process utilizes a double layer one-side “stop-off” coating to prevent the molten Al from adhering to the steel surface. The “Stop-off” coating is removed by simple mechanical brushing after hot dipping. The characteristics of this product by above mentioned process are: 1) The steel side was as clean as a conventional cold rolled surface and showed no trace of the “stop-off” layer. Thereby, phosphating and ED painting were performed. 2) In the salt spray test data was obtained from zinc and Al coated steel surfaces; the coatings on both surfaces being of equal thickness.

The findings presented in this paper are part of a long term project aimed at raising the science of heat transfer in internal combustion engine cooling galleries. Initial work has been undertaken by the authors and an experimental facility is able to simulate different sizes of coolant passages. External heat is applied and data for the forced convective, nucleate boiling and transition or critical heat flux (CHF) regimes has been obtained. The results highlighted in this paper attempt to quantify the effects of cooling passage surface roughness on the nucleate boiling regime. Tests have been conducted using aluminium test pieces with surface finishes described as smooth, intermediate and as-cast. It has been found that the as-cast surface increases the heat flux density in the nucleate boiling region over that of the smooth and intermediate surfaces.

MONOGAL is a coated steel developped to improve the corrosion resistance of exposed automotive body applications. Its process os based on the brittleness of the η zinc coating in a range of temperatures below the melting point of the zinc. MONOGAL is produced on a hot dip galvanizing line; at the exit of the pot the free zinc is brushed off the light side of the differentially coated sheet. Side 1 of MONOGAL presents a very thin and continuous layer of iron-zinc diffusion alloy with no free zinc. Side 2 is a standard G90 or G60 zinc coating. The iron-zinc alloy layer has excellent anti-galling properties which improve the formability of MONOGAL over two side hot dip galvanized steel with the same r value. MONOGAL also shows good weldability, paintability and corrosion resistance.

This specification covers the characteristics of glass beads used for peening, and provides for standard glass bead size numbers.

This specification covers the characteristics of glass beads used for peening, and provides for standard glass bead size numbers.

Diesel engines are coming under stricter requirements to reduce emissions. particularly those of particulates and nitrogen oxides (NOx). Recently, the U. S. EPA put into place staged requirements for heavy duty diesel engines in urban bus applications which are aimed at ultimately bringing pre-1994 engines into particulate emissions compliance with 1994 heavy duty on-road truck standards (0. 1 g/bhp-hr TPM). This reflects the need to control emissions in crowded urban environments. Zirconia based ceramic combustion management coatings, although originally developed for adiabatic or low heat rejection engines to boost thermal efficiency, have also been shown to contribute to the reduction in diesel emissions. Heavy duty transient testing of rebuilt 2-stroke MUI diesel bus engines equipped with stabilized zirconia based coatings applied by thermal spray process have shown significant reduction in exhaust opacity relative to a baseline, uncoated engine.

The process considerations, manufacturability, corrosion properties, paintability, weldability, and formability of nominal 9 to 15 percent electrodeposited zinc-nickel (Zn-Ni) alloy-coated sheet steels for automotive applications were reviewed. Zn-Ni coatings were selected for use in automobile body panels by several automakers because of their ease of manufacturing, forming, and welding. Although Zn-Ni coatings may be easily manufactured into autobody panels without a change in production procedures, these coatings exhibit poor paintability and poor corrosion resistance, and would be risky to expose in the U.S. automotive environment at the specified 20 to 40 g/m2 coating weights. Zn-Ni coatings will not provide the cosmetic corrosion protection of zinc or zinc-iron (Zn-Fe) coatings, particularly on exterior autobody panels in a fully painted condition.

Zinc-manganese alloy electroplated has been developed for automotive body panel applications. The product is manufactured on a conventional electrogalvanizing line using an electrolyte containing zinc sulfate, manganese sulfate and sodium citrate. Electroplated steel with an alloy content of 30-50% manganese exhibits excellent corrosion resistance both as-produced and after painting. Zinc-manganese coatings also show good workability and voidability. Accordingly, this product is suitable for both unexposed parts and the interior surfaces of exposed parts. Finally, zinc-manganese electroplated steel displays good wet adhesion and anti-cratering characteristics so that the product can also be used for exposed applications as automotive body panels.

Zinc-coatings with a substantial Magnesium content have been in use for over 30 years by now. Unlike the well-established Zn-Al-Mg coatings originating from Japan which have significant higher alloying contents applied mainly for building applications, this Zinc Magnesium Aluminum coating (ZM) is also specifically designed to meet the requirements of car manufacturers. The ZM coating introduced by voestalpine, corrender, is in the upper range of ZM-alloying compositions, which was set by VDA (German Association of the Automotive Industry) and SAE to be within 1.0 to 2.0 wt. % Mg and 1.0 to 3.0 wt. % Al. The properties of these “European” Zinc-Magnesium coatings are well comparable within this range. Compared to GI and GA ZM coatings exhibit significant advantages in the press shops with its excellent formability and reduced galling and powdering respectively which is a significant advantage for the forming of outer panels.

For over a decade, industry prognosticators have been predicting that the use of plastics by automakers would soon surpass the deployment of metals in automobiles, While there is no denying that plastics have made inroads, it recently has become apparent that metal will retain its position as the prime car material for the foreseeable future. One reason for the revised forecast is the development of improved zinc coatings for the automotive industry. Such material as electrogalvanized and Galfan™ are shaping up as steel's saviors when it comes to ensuring that metal will continue to play the major role on car assembly lines. Meanwhile on the other side of the equation, developments in zinc die casting technology have taken the edge off plastics' forward thrust into both functional and decorative car part applications.

Copper and brass radiators have served the automobile industry for many years using traditional fabrication processes. Demand for newer and stronger radiators with lighter weight for the modern vehicles prompted investigation of alternate materials. Properties of zinc alloys and their compatibility with brass suggested these could be used for radiator manufacture. Many zinc alloy compositions were investigated in the initial studies, because a solder alloy has to have many positive attributes. The first screening studies evaluated the ability of the solder to spread over copper and brass surfaces, representing tube, fin, and header materials. The second most important feature was the melting range of the developed alloy. In order to retain the anneal resistance of the fin and temper in the tube it was desirable to have a zinc solder with a melting temperature at 800°F or less.

The critical component for maintaining uniform zinc phosphate coatings on aluminum is fluoride. The control of free fluoride is critical to the operation of the process, because aluminum is dissolved in a zinc phosphate bath as a step in the coating reaction. If the dissolved aluminum is not removed from the bath, it will inhibit the formation of coatings on all metals being treated. This paper presents the characteristics and composition of zinc phosphate coatings on aluminum and steel, and lists some practical considerations of the transition from steel to aluminum components. Some possible problem areas discussed are: galvanic corrosion, underpaint quality, surface finish, electro-painting, and new paint surfaces.

The extrusion of zinc alloys, with special reference to zinc-titanium alloys, is described. Parameters for this process are defined. The excellent tensile and creep properties obtained in a typical extruded zinc-titanium alloy are presented. Extruded zinc with a quality copper-nickel-chrome plated finish offers a new approach to the production of automotive trim and of similar products.

Many papers have been written for SAE on electrochemical metallizing, a modern term for “selective” or “brush” plating. These papers have dealt primarily with the aerospace industry, including the use of non-embrittling cadmium LHE® coatings for corrosion protection on aircraft. Shadowed by 30 years of successes in the aerospace industry, electrochemical metallizing corrosion protection in the automotive industry is often overlooked. Specifically, the use of selectively applied zinc coatings for corrosion protection on wheel hubs during manufacture has proven integral at several European automotive manufacturers. In the past, environmental conditions have corroded both the hubs and wheels of automobiles. Quite often the corrosion is in the microscopic gap between the hub and the wheel, which over time causes the wheel to seize and prevents removal. This has been frustrating to both stranded motorists and shop mechanics.

Zinc die casting products and metal casting processes continue to evolve for the benefit of end users. Through cooperative global research programs continuous improvements are still being made to the broad range of excellent mechanical properties, easy castability and the wide choice of finishes available for zinc die castings. Recent advances will be highlighted with case histories specific to automotive applications.

Because of the drastic chilling involved in die casting and the fact that the solid solubilities of both aluminum and copper in zinc change with temperature, these alloys are subject to some aging changes, one of which is a dimensional change. Both of the alloys undergo a slight shrinkage after casting, which at room temperature is about two-thirds complete in five weeks. It is possible to accelerate this shrinkage by a stabilizing anneal, after which no further changes occur. The recommended stabilizing anneal is 3 to 6 h at 100 °C (212 °F), or 5 to 10 h at 85 °C (185 °F), or 10 to 20 h at 70 °C (158 °F). The time in each case is measured from the time at which the castings reach the annealing temperature. The parts may be air cooled after annealing. Such a treatment will cause a shrinkage (0.0004 in per in) of about two-thirds of the total, and the remaining shrinkage will occur at room temperature during the subsequent few weeks.

HOT-DIP galvanized steel sheets have been increasingly used in the automotive industry. However, two major problems occur during spot-welding because of the presence of zinc: 1/ Welding parameters differ from those used for bare sheets 2/ Electrodes life span often decreases. Two products have been thoroughly tested: 1/ Usinor MONOGAL® sheet 2/ Two-sides hot-dip galvanized sheet with various zinc-coating thicknesses. Welding parameters have been optimized by the determination of weldability lobes. Both products present a wide range of intensities, provided that weld current and electrode force are increased. The effect of an enventual variation of zinc-coating thickness is negligible. Electrodes life satisfies the FORD 2000 spot welds acceptance test. At last, temperature measurements inside the electrodes have shown the interest in increasing the electrodes tip diameter.

Press-hardening steels get more and more popular for body in white applications as an approach to meet the demands of passenger safety and CO2 reduction. Unlike the larger part of the structure that is typically zinc coated, the majority of the PHS parts is either uncoated or aluminum silicon coated. This paper shall give an overview of press-hardening steels with zinc coatings with detailed results for corrosion resistance, weldability and mechanical properties for strength levels of 490 to 1800 MPa. Furthermore as for zinc coated material maintaining a robust press-hardening process is of even higher importance than for uncoated or AlSi coated material. A range of different processes including indirect and direct process are shown in detail. Especially the topic of micro-cracks, mechanisms and avoidance of micro-cracks in the direct process will be discussed. Results from industrial and semi industrial production are shown.

Provision of a layer of zinc on aluminium to provide the fillets for soldering is well established but this usually necessitates a thick layer of zinc (>30μm) and soldering at temperatures below 450°C. New technology has been developed to enable sound joints to be made on aluminium heat exchangers using a much thinner layer of zinc (4 to 8 μm typically) on the aluminium component to provide the joint. By the correct combination of flux and zinc coating thickness, joints have been obtained over a wide range of heating conditions. Preferred temperature cycles are similar to those used by the industry today for brazing of Aluminium:Silicon braze-clad aluminium components which should facilitate tranfer by industry to the new technology.