Aluminum processing parameters

The third contribution is particularly devoted to the concept of so-called single source precursors (SSPs). SSPs contain all the atoms of the different elements necessary for the deposition of the desired material in one single molecule. One motivation for using this concept is to simplify the accompanying gas-phase reactions and thus reduce the process parameters to be controlled and optimised. However, SSPs may offer a unique chance of depositing metastable materials that cannot be derived by other methods. M. Veith and S. Mathur provide such an example in their paper entitled Single-Source-Precursor CVD Alkoxy and Siloxy Aluminum Hydrides . 

Table 8.2 The influence of different process parameters on the nanostructure of aluminum deposits. In the case of additive addition benzoic acid was used.

Romundstad, R, Haldorsen, T, and Ronneberg, A. (1999). Exposure to RAH and fluoride in aluminum reduction plants in Norway Historical estimation of exposure using process parameters and industrial hygiene measurements. Am J Ind Med 35, 164-174. 

K.J. Colligan, J. Xu, and J.R. Pickens, Welding Tool and Process Parameter Effects in Friction Stir Welding of Aluminum Alloys, Friction Stir Welding and Processing II, K.V. Jata, M.W. Mahoney,... 

In this chapter, the FSW process parameters that can affect microstructure/property distributions in aluminum alloy friction stir welds are described. The chapter includes a brief description of the main classes of aluminum alloys, the processing routes (thermomechanical treatments) typically associated with each class, and how FSW parameters can be manipulated, in a general way, to modify the microstructure and... 

C. Gallais, A. Denquin, A. Pic, A. Simar, T. Pardoen, and Y. Brechet, Modelling the Relationship between Process Parameters, Microstructural Evolutions and Mechanical Behavior in a Friction Stir Welded 6xxx Aluminum Alloy, Proc. Fifth Int. Symp. on Friction Stir Welding, Sept 2004 (Metz, France), TWI... 

W.J. Arbegast and A.K. Patnaik, Process Parameter Development and Fixturing Issues for Friction Stir Welding of Aluminum Beam Assemblies, Proceedings of the 2005 SAE AeroTech Conference, Oct... 

Similar to aluminum, submicrometer size pores can also be formed on titanium surface. Titanium surface can be anodized to generate pores in the presence of fluoride which required very long anodization time. Anodization of titanium in sulfuric and phosphoric acid also leads to the formation of oxide layer, however it is very dense, but at very high voltage breakdown of oxide layer leads to the formation of pores. The size and number of pores can be controlled by controlling the process parameters. Fig. 12.12 shows the surface of titanium with porous oxide film containing submicron size... 

In the following, the Sigal process will be described in more detail. The typical complex in this process is shown in Figure l. 9 The deposition of aluminum from these complexes is a rather slow process. A mechanism was discussed by Kautek and Birkle. Typical process parameters are 5-30 V, 0.2-2 A dm" DC, and 90 °C. 

The abrasive belt used for these tests was a 3M Flex diamond belt with 125 ULm grit size. The length of the belt is 2133.6 mm and the width is 101.4. The test samples were extruded aluminum oxide 96%, cylindrical shaped, with an average length Lave =101.25 mm (Figure 7.2). The sample material density is p = 3.702 g/crn. Taking into account that these were preliminary tests and that there is very limited data on this type of process, we opted for a full factorial design of the experiments. Thus, the variable process parameters were... 

Mixed copper/zinc catalysts with high copper-to-zinc ratios are widely used as catalysts for low-pressure methanol production and for low-temperature shift reaction [2, 31], see also Chapter 15. These catalysts are commonly made by coprecipitating mixed-metal nitrate solutions by addition of alkali. Li and Inui [32] showed that apart from chemical composition, pH and temperature are key process parameters. Catalyst precursors were prepared by mixing aqueous solutions of copper, zinc, and aluminum nitrates (total concentration 1 mol/1) and a solution of sodium carbonate (1 mol/1). pH was kept at the desired level by adjusting the relative flow rate of the two liquids. After precipitation was complete, the slurry was aged for at least 0.5 h. When the precipitation was conducted at pH 7.0, the precipitate consisted of a malachite-like phase (Cu,Zn)C03(0H)2 and the resulting catalysts were very active, while at pH < 6 the formation of hydroxynitrates was favored, which led to catalysts less active than those prepared at pH 7.0 (Figure 7.8). 

Anodization is the electrolytic oxidation of an anodic metal surface in an electrolyte. The oxide layer can be made thick if the electrolyte continually corrodes the oxide during formation. Barrier anodization uses borate and tartrate solutions and does not corrode the oxide layer. Barrier anodization can be used to form a very dense oxide layer on some metals ( valve metals) including aluminum, titanium, and tantalum. The thickness of the anodized layer is dependent on the electric field, giving a few angstroms/volt (about 30 A/volt for aluminum). The process is very sensitive to process parameters, in particular to tramp ions, which may cause corrosion in the bath. Anodized Ti, Ta, and Nb are used as jewelry where the oxide thickness provides colors from interference effects and the color depends on the anodization voltage. In anodic plasma oxidation, plasmas are used instead of fluid electrolytes to convert the surface to an oxide. 

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