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Technical Paper

• Oxidation Stability • Shear Stability • Rubber Swell Properties of Automatic Transmission Fluids

A NEW TEST is described for studying the oxidation stability of automatic transmission fluids (ATF). The test shows an excellent correlation with transmission oxidation tests and points out the importance of time as a variable in such studies. Carefully controlled automobile dynamometer tests have been used to study the shear stability of ATF's. Data are presented showing a comparison of driving conditions, transmissions, and V.I. improvers on shear stability. Results are related to the 50-hr Hydra-Matic durability test. The poor reproducibility of rubber swell measurements on commercial transmission seals is due largely to differences in the rubber compounds. A great improvement in the reproducibility may be made by taking into account the specific gravity of the rubber sample.*
Technical Paper

“Trapless” Trap – A Catalytic Combustion System of Diesel Particulates Using Ceramic Foam

“Trapless” Trap, which makes possible the effective collecting of particulates in diesel exhaust gas and their simultaneous combustion has been developed by use of a ceramic foam in combination with catalysts containing copper salt. From a TEM photograph, it was observed that the particulate was rapidly oxidized by mobile copper ion, showing worm-eaten like spots. Screening of various base metal salts by TGA presented CUCl2-KCl-NH4VO3 and CuCl2-KCl-(NH4)6Mo7O24 as very active catalysts for diesel particulate oxidation. They had thermal stability up to 900°C when they were supported on titania. The results obtained by measuring the back pressure using 1.8L diesel engine suggest the above trap to be a self-cleaning trapless trap.
Technical Paper

“RoHS” Compliant Chrome - Free Conversion Coating for Aerospace Manufacturing

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.
Technical Paper

“MONOGAL”: A New Anti-Corrosion Material for the Automotive Industry

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.
Technical Paper

“DELRIN” ACETAL RESIN —a new engineering material

“DELRIN” is a new thermoplastic which offers high strength, excellent thermal stability, good fatigue life, low creep, and excellent solvent resistance. This paper describes the physical and chemical properties of the material, and the range of possible uses. The material is easily fabricated into complex shapes by standard injection-molding techniques. Also, it can be easily joined to itself or to other materials. The authors think that the material offers advantages over metals in its good fric-tional properties, abrasion resistance, and corrosion resistance.
Technical Paper

“Condensation – Why it Needs to be Addressed in Every Aircraft”

A wide body aircraft carries almost a half–ton of water and ice between the cabin and skin of the aircraft. The water can get on wires and connectors, which can cause electrical problems, cause corrosion and rust, and, eventually, “rain in the plane”. The speaker is the CEO of CTT Systems that has developed a system that solves the condensation by using dry air. The speaker will discuss how condensation can be prevented and how airlines can also save maintenance costs in the process. This topic is relevant for the attendees at the Aerospace Expo, as they are decision makers who need to be aware of this issue. It is also important for the MRO shows as the attendees are on the front lines of dealing with this problem.
Technical Paper

Zn-Ni Plating as a Cadmium Alternative

In a 2-year program sponsored by SJAC, an aqueous electroplating process using alkaline Zn-Ni with trivalent chromium post treatment is under evaluation for high strength steel for aircraft application as an alternative to cadmium. Commercial Zn-15%Ni rack/barrel plating solutions are basis for plating aircraft parts or fasteners. Brightener was reduced from the original formula to form porous plating that enables bake-out of hydrogen to avoid hydrogen embrittlement condition. Properties of the deposit, such as appearance, adhesion, un-scribed corrosion resistance, and galvanic corrosion resistance in contact with Al alloy, were evaluated. Coefficient of friction was compared with Cd plating by torque-tension measurements. Evaluation of the plating for scribed corrosion resistance, primer adhesion, etc. will continue in FY2007.
Technical Paper

Zinc-Nickel Alloy Coatings-A Technical Review of Published Literature

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.
Technical Paper

Zinc-Manganese Alloy Electroplated Steel for Automotive Body

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.
Technical Paper

Zinc-Magnesium-Aluminium (ZM)-HDG-Coated Steel Sheet for Structural Parts to Outer 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.
Technical Paper

Zinc Phosphate Pretreatment Systems for Aluminum-Steel Assemblies

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.
Technical Paper

Zinc Electrochemical Metallizing for Corrosion Protection of Automobile Wheel Hubs

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 Alloys

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.
Technical Paper

Zinc Coated Press-Hardening Steel - Challenges and Solutions

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.
Technical Paper

Zinc Casting Alloys—A Comparative Properties Analysis

The preceeding presentation explained the compositions of the zinc alloys. Now we can examine the properties that these combinations give rise to. In doing so, we must first understand the importance of each property to the design of any component. One must consider each of the properties individually so as to gain an understanding of cumulative effects and the relative importance of each property to the final application. The most effective way to attack the problem is to analyze the part's requirements with respect to applied stresses, environmental and operating conditions and economic constraints. While there are many mathematical models available to enable numerical analysis of property evaluations, they all rely on the same basic principle: The Total Systems Approach. That is, the consideration of all aspects of design. Properties evaluation is a critical step in this process.
Technical Paper

Zero-Waste PVD Cadmium for High Strength Steels

In spite of environmental issues related to cadmium and its electroplating process, electroplated cadmium is still extensively used in the aerospace and defense sectors. This trend is likely to continue especially for high strength steels because cadmium provides the best known corrosion and embrittlement protection for this application. Consequently, the environmental concerns related to the cadmium electroplating have been addressed using an alternative Zero-waste Physical Vapor Deposition (Z-PVD). This method does not use liquids, it recycles cadmium in situ, and is free of hydrogen embrittlement. The Z-PVD process is now in commercial production for the aerospace fasteners. The quality of the coatings has been at least equal to that of the electroplated cadmium.