Effect of Copper on Corrosion of Forged AlSi1MgMn Automotive Suspension Components

Recently, modifications in the alloy composition and the manufacturing process cycle were proposed to achieve a more uniform structure with no evidence of coarse grains across the section of the AlSi1MgMn alloys. Cu was added to the AlSi1MgMn alloy to improve its age hardening capacity without a separate solution heat treatment. However, Cu addition degrades the corrosion resistance of this alloy due to the formation of Al-Cu precipitates along the grain boundaries that are cathodic with respect to the aluminum matrix and thus encourage intergranular corrosion. The present work was undertaken to identify the impact of Cu addition on the corrosion properties of AlSi1MgMn alloys with different Cu contents. A series of AlSi1MgMn alloys with 0.06-0.89 wt.% Cu were tested in order to identify an optimum level of Cu addition

Characterization of eggshell-derived hydroxyapatite on Ti6Al4V metal substrate coated by sol-gel method

The aim of this work was to synthesize hydroxyapatite (HAp) by sol-gel route using eggshell and triethyl phosphite as calcium and phosphorus precursors, respectively. After the preparation of homogeneous solution with aging period for 24 h, hydroxyapatite (HAp) sol-gel coatings were made on Ti6Al4V substrate. Polyethylene glycol (PEG) and triethanolamine (TEA) were added to HAp solution to enhance morphological structure of coatings. PEG- and TEA-added solutions and coatings were labeled as P-Hap and T-Hap, respectively. The coating process was carried out by spin coating method, and the coated samples were heated up to 600 degrees C for 1 h. Phase development of coatings and dried powder and morphologies of coatings upon heat treatment were detected by XRD and SEM, respectively. Thermal behavior of obtained powder were investigated with DTA/TGA. Surface roughness was determined by XP2 surface profilometer. It was found that all the samples at RT showed amorphous structure and transformed at 600 degrees C to well-crystallized HAp-phase with no beta-TCP. Morphological results indicated that T-HAp coating showed the best morphology with crack-free uniform porous structure, which is necessary for biocompatible implants. P-HAp coating showed non-uniform porous structure with large cracks, whereby HAp coatings had similar structure to T-HAp coatings but with much less porosity

Production and Characterization of Al-Si Coatings Fabricated by Mechanical Alloying Method on Inconel 625 Superalloy Substrates

Inconel superalloys are used substantially in high-temperature environments. However, these alloys suffer from corrosion and wear. Attempts to overcome these drawbacks involve coating the metal with different techniques and materials. In this study, a new method with increasing potential was utilized. Using the mechanical alloying process in a planetary ball mill vial, alloying and the Al-Si coatings were concurrently achieved on Inconel 625 substrates. Different process control agent (PCA) ratios, milling ball diameters, and milling times were used to improve coating properties. Macro and microstructure, morphology, microhardness, and roughness values of samples were evaluated and compared. Additionally, crystallographic and cross-sectional properties were investigated in order to optimize the processing conditions. The results indicated that increasing the diameter of the grinding ball enhanced the hardness and thickness of these coatings and increased the roughness values. Longer processing time also enhanced the thickness with mechanical values. However, under these conditions, coating homogeneity decreased, and incompatible regions were formed on the coatings. PCA content brought a refined grain structure, hence showed better mechanical properties. On the other hand, processing time should be increased to get a denser and thicker protective layer against the operational conditions

Green alternative treatment for cellulosic fibers: ionic liquid modification of Abelmoschus esculentus fibers with methyl-tri-n-butyl ammonium methyl sulphate

In this research, Okra (Abelmoschus esculentus) fibers were treated with an ionic liquid, methyl-tri-n-butyl ammonium methyl sulphate, to modify surface of the fibers. The fibers were exposed to aqueous ionic liquid solutions at different concentrations such as; 2, 5, 10 and 20 w/v% at ambient temperature. Ionic liquid treatment led to enhanced surface hydrophobicity of the okra fibers by means of increase in surface carbon/oxygen ratio. The proportion of C-C and C-H bands in the okra fibers were increased as a result of the treatment. The untreated and treated okra fibers gave similar crystalline index (CI) values. The CI results varied between 61.12 and 65.92%. Thermal stability of the fiber deteriorated after the treatment. However, char yield values increased indicating possibly enhanced flame retardancy after the treatments. Scanning electron microscopy observation confirmed the existence of ionic liquid both in intercellular gaps and on the surface of the okra fibers

Characterization of a new natural cellulose based fiber from Hierochloe Odarata

The study was undertaken to investigate the usability of Hierochloe Odarata fibers as a novel reinforcement for polymeric composites. The fibers were extracted from Hierochloe Odarata plant, which is cultivated in Uzunalan, canakkale which is in the western part of Turkey. The cellulose, hemicelluloses and lignin contents of Hierochloe Odarata fibers were obtained as 70.4, 21.5, and 8.1%, respectively. The oxygen/carbon ratio of 0.48 may indicate the hydrophilic surface structure of Hierochloe Odarata fibers. The crystallinity index of these Hierochloe Odarata fibers was determined as 63.8% according to the Segal formula. Hierochloe Odarata has 105.7 MPa maximum tensile strength, 2.56 GPa Young's modulus and 2.4% maximum breaking elongation. The maximum degradation temperature and the char yield of the fibers were obtained as 352 degrees C and 12.5%, respectively. After physical and chemical properties were characterized in the study, it was concluded that Hierochloe Odarata fibers can be an alternative sustainable material for polymer-based composites as potential reinforcement. Graphic abstrac