Synthesis of amorphous carbon nitride using reactive ion beam sputtering deposition with grazing bombardment

Amorphous carbon nitride (a-C:N) thin films were synthesised on steel substrates using reactive ion beam sputtering deposition (RIBSD). A single ion beam is arranged to sputter the graphite target at 75° incidence and concurrently bombard the growing film at grazing incidence angles of the ion beam. Nanoindentation, Raman spectroscopy, FTIR, FT-Raman and XPS were employed to characterise the mechanical and structural properties of the films. It was found that grazing incident bombardment has a significant effect on film structure through an increase in nitrogen content and formation of nitrogen doped structure.     

Metal Organic Chemical Vapour Deposited Thin Films of Cobalt Oxide Prepared via Cobalt Acetylacetonate

The single solid source precursor, cobalt (Ⅱ) acetylacetonate was prepared and characterized by infrared spec-troscopy. Thin films of cobalt oxide were deposited on soda lime glass substrates through the pyrolysis (metal organic chemical vapour deposition (MOCVD)) of single solid source precursor, cobalt acetylaceto-nate, Co[C5H7O2]2 at a temperature of 420℃. The compositional characterization carried out by rutherford backscattering spectroscopy and X-ray diffraction (XRD), showed that the films have a stoichiometry of Co2O3 and an average thickness of 227±0.2 nm. A direct energy gap of 2.15±0.01 eV was calculated by the data obtained by optical absorption spectroscopy. The morphology of the films obtained by scanning electron mi-croscopy, showed that the grains were continuous and uniformly distributed at various magnifications, while the average grain size was less than 1 micron for the deposited thin films of cobalt oxide.     

Failure Analysis of Boat Rudder Fitting Fabricated from a Type 304 Stainless Steel

The failure of a type 304 stainless steel component subassembled by welding and used on a boat in a marine environment was investigated. The mechanism of damage initiation and the cause of final failure were investigated. Initial examination of the component indicated deep branching cracks that were thought to have developed during service. The combination of microhardness test and finite element modeling (FEM) was employed to probe micromechanical properties of the damaged area. The corrosion observed was followed with scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). FEM analysis suggests that the cracked area had been subjected to tensile stresses in service. Microhardness across the welded section did not show any mechanical degradation across the weld and heat-affected zone. The cracked area was evidently corroded, and the microanalysis in the SEM/EDS indicated the presence of corrosion products. Regions around the cracks especially at the root of the crack were found to be severely depleted of Ni. It is evident that the primary course of failure was from the cracking from SCC attack and that the pitting observed is a secondary effect in the cracked region.     

Three-stage crystallization mechanism in Fe83.5Nb7B8.5Al1 amorphous alloy

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Comparative assessment of Australian fly ash and conventional concrete bricks

A comparative study of the chemical composition, mineralogy, morphology and crushing strengths of fly ash bricks, conventional concrete bricks and fly ash samples has been undertaken. The main chemicals present in the products were silica and alumina while their main minerals were quartz, mullite, illite, vaterite, and calcite. Elemental analysis by XPS showed that the major elements in the samples were oxygen, silicon, carbon, calcium and aluminium; and scanning electron microscopy revealed that the fly ash samples consist of spherically‐shaped particles with surface attachment containing needle‐like particles. Compared with conventional concrete bricks, fly ash bricks generally have higher atomic silicon and crushing strengths but lower crystalline silica. The implication of the results on the suitability of fly ash bricks as replacements for conventional concrete bricks in the building industry is discussed from the point of view of human health and occupational safety. Copyright © 2004 Society of Chemical Industry     

Analysis on Structure and Properties of Diamondlike Carbon Films from Ion Beam Deposition

Diamondlike carbon (DLC) films from a primary ion beam deposition system, were examined using nanoindentation, SEM, AES, XPS, and Raman Spectroscopy. The films have hardness values ranging from 21 to 29 GPa. The results of SEM and AES show that the films are predominantly carbon without any crystalline features, and that nitrogen is incorporated as nitrogen is used as the ion beam source. XPS, and Raman Spectroscopy confirm that the films are amorphous carbon with a combination of sp³ with sp² bonding. It is concluded that DLC films can be directly deposited on steel using a single ion beam to sputter the solid target, and the structure and properties of DLC largely depend on ion beam source.     

Microwave processing of adhesive joints using a temperature controlled feedback system

Previous experiments have shown that microwave curing of epoxies reduces the curing time and could lead to improvements in the mechanical properties of the cured epoxies. Precise temperature control is important as inadequate control may lead to thermal “run-away”, resulting in localized material damage. Consequently, the main objective of the present work is to use temperature for controlling the intensity of microwave radiation during the adhesive curing process. Using microwave energy delivered through a slotted waveguide at a frequency of 2.45 GHz, and with the power varied between 300 and 600 W, three engineering thermoplastics or adherends were joined by curing two types of “two-pack” epoxy adhesives. Subsequently, the bond strengths of the microwave cured samples were compared to those of the specimens cured in ambient conditions by subjecting the joined samples to shear loading. The results obtained indicate that the samples cured with microwave under a temperature feedback control protocol achieved higher bond strengths after curing for only a fraction of the time required for ambient curing. It can therefore be inferred that, with an adequate temperature control strategy, increased efficiency of curing, higher quality of adhesive joint, and improved bond strength can be achieved when joining thermoplastics.