A calibration for surface analysis on aluminium alloys by RF-Glow-Discharge Optical Emission Spectrometry

Glow-Discharge Optical Emission Spectrometry (GD-OES) is a powerful technique for the rapid analysis of elements in a solid surface as a function of depth. DC-GD-OES allows depth profiling on electrically conductive surfaces only, and has proven to be difficult for the analysis of insulating layers, such as oxides. However, the technique of radio-frequency (RF) GD-OES has the advantage of being able to depth profile through multiple layers, both conducting and insulating. In this work, a LECO GDS- 850A spectrometer was calibrated for aluminium, oxygen, and other elements, with the RF source installed. A quantitative depth profile for a sample of tempered aluminium alloy 7475 is presented and compared with earlier work[1,2].

A life cycle inventory of aluminium die casting

As part of an ongoing project, a life cycle inventory (LCI) of aluminium high pressure die casting (HPDC) has been collected. This has been conducted from the view of an individual product and also the entire process. The objective of the study was to analyse the process and suggest changes to reduce environmental impacts. One modem aluminium high pressure die casting plant located in Victoria, Australia was evaluated and modelled. Site specific data on energy and materials was gathered and the process was modelled using a typical automotive component. The paper also presents our experience and methodology used in this inventory data collection process from the real industry for LCA purposes. The inventory data collected itself reveals that the HPDC process is energy intensive and as such the major emissions were from the use of natural gas fired furnaces and from the brown coal derived electricity. It is also found the large environmental benefits of using secondary aluminium over primary aluminium in the HPDC process. A detailed LCA is being cal1ied out based on the inventory obtained.

Influences of steady and cyclic die rotation on the compression of aluminium

A series of experiments are reported for compression of an aluminum cylinder with monotonic and cyclic die rotation. When the die is monotonically rotated, a higher angular velocity or a lower compression speed of the tool leads to a greater load reduction in comparison of that seen with a stationary die. The test results also show that cyclic die rotation causes a cyclic fluctuation in the load-displacement curve. During the die deceleration phase, the compression load increases until it reaches the level obtained in conventional compression with stationary dies. However, the compression load is observed to reduce to levels lower than those obtained in monotonic rotating compression tests during the die acceleration phase. The frequency of rotating direction change seems to affect the position of load peaks only, not the amplitude of the peaks.

Water repellency, near-saturated infiltration and preferential solute transport in a macroporous clay soil

Little attention has been paid to the possibility that soil water repellency could enhance non-equilibrium water flow and solute transport through macropores present in structured clay soils. In this study, we measured infiltration and solute transport in a clay soil under near-saturated conditions in both the field using tension infiltrometers and in the laboratory on undisturbed soil columns. Measurements were made on adjacent plots under grass and continuous arable cultivation. Steady-state field infiltration rates measured using water and ethanol as the infiltrating fluids demonstrated that the soil macroporosity under grass was better developed, but that much of the structural pore system was inactive due to water repellency. No water repellency was detected on the arable plot disturbed by tillage. Dye tracing showed that the conducting macroporosity was largely comprised of earthworm channels in the grassed plot and inter-aggregate voids resulting from ploughing in the arable plot. Tracer breakthrough curves measured on field-dry soil indicated rapid macropore transport in columns taken from both plots, although the degree of non-equilibrium transport appeared somewhat stronger under grass. This result, which was attributed to water repellency, was also consistent with the larger flow-weighted mean pore size found in the field infiltration experiments. It is concluded that water repellency in undisturbed structured clay soils can have significant effects on the occurrence of non-equilibrium water and solute transport in macropores.

Enhanced tensile ductility of an ultra-fine-grained aluminium alloy

Aluminum alloy 6082 was subjected to equal-channel angular pressing (ECAP), which resulted in an ultra-fine-grained (UFG) microstructure with an average grain size of 0.2–0.4 μm. There was a pronounced effect of the grain refinement on the strain-rate sensitivity and tensile ductility. The Hart criterion of tensile necking fails to explain the observed ductility of the UFG material at low strain rates. A correlation between the observed stronger-than-expected ductility and a tendency to microshear band formation at low strain rates was established.

Nanostructures and nanoporosity in thermoset epoxy blends with an amphiphilic polyisoprene-block-poly(4-vinyl pyridine) reactive diblock copolymer

Nanostructured thermoset blends were prepared based on a bisphenol A-type epoxy resin and an amphiphilic reactive diblock copolymer, namely polyisoprene-block-poly(4-vinyl pyridine) (PI-P4VP). Infrared spectra revealed that the P4VP block of the diblock copolymer reacted with the epoxy monomer. However, the non-reactive hydrophobic PI block of the diblock copolymer formed a separate microphase on the nanoscale. Ozone treatment was used to create nanoporosity in nanostructured epoxy/PI-P4VP blends via selective removal of the PI microphase and lead to nanoporous epoxy thermosets; disordered nanopores with the average diameter of about 60 nm were uniformly distributed in the blend with 50 wt% PI-P4VP. Multi-scale phase separation with a distinctly different morphology was observed at the air/sample interface due to the interfacial effects, whereas only uniform microphase separated morphology at the nanoscale was found in the bulk of the blend.

Quantitative assessment of through-thickness crack size based on Lamb wave scattering in aluminium plates

The interaction of Lamb wave modes at varying frequencies with a through-thickness crack of different lengths in aluminium plates was analysed in terms of finite element method and experimental study. For oblique-wave incidence, both numerical and experimental results showed that the wave scattering from a crack leads to complicated transmission, reflection and diffraction accompanied by possible wave-mode conversion. A dual-PZT actuation scheme was therefore applied to generate the fundamental symmetrical mode (S0) with enhanced energy to facilitate the identification of crack-scattered wave components. The relationship between crack length and the reflection/transmission coefficient obtained with the aid of the Hilbert transform was established, through which the crack length was quantitatively evaluated. The effects of wavelength of Lamb waves and wave diffraction on the properties of the reflection and transmission coefficients were analysed.

Tensile deformation of a ultrafine-grained aluminium alloy: micro shear banding and grain boundary sliding

This work investigates the relationship between the strain rate and the ductility and the underlying deformation mechanisms in an ultrafine-grained Al6082 alloy. At room temperature the uniform elongation of the material exhibits a marked increase with decreasing strain rate. This effect is related to the activation of micro shear banding, which is controlled by grain boundary sliding. The contribution of these mechanisms to uniform elongation is estimated. It is proposed that the grain boundary sliding suppresses the transformation of micro shear bands into macro shear bands. The activity of other deformation mechanisms during plastic deformation of the ultrafine-grained material is also discussed.

Effects of ovariectomy and estrogen on ischemia-reperfusion injury in hindlimbs of female rats

The effects of estrogen and ovariectomy on indexes of muscle damage after 2 h of complete hindlimb ischemia and 2 h of reperfusion were investigated in female Sprague-Dawley rats. The rats were assigned to one of three experimental groups: ovariectomized with a 17-estradiol pellet implant (OE), ovariectomized with a placebo pellet implant (OP), or control with intact ovaries (R). It was hypothesized that following ischemia-reperfusion (I/R), muscle damage indexes [serum creatine kinase (CK) activity, calpain-like activity, inflammatory cell infiltration, and markers of lipid peroxidation (thiobarbituric-reactive substances)] would be lower in the OE and R rats compared with the OP rats due to the protective effects of estrogen. Serum CK activity following I/R was greater (P < 0.01) in the R rats vs. OP rats and similar in the OP and OE rats. Calpain-like activity was greatest in the R rats (P < 0.01) and similar in the OP and OE rats. Neutrophil infiltration was assessed using the myeloperoxidase (MPO) assay and immunohistochemical staining for CD43-positive (CD43+) cells. MPO activity was lower (P < 0.05) in the OE rats compared with any other group and similar in the OP and R rats. The number of CD43+ cells was greater (P < 0.01) in the OP rats compared with the OE and R rats and similar in the OE and R rats. The OE rats had lower (P < 0.05) thiobarbituric-reactive substance content following I/R compared with the R and OP rats. Indexes of muscle damage were consistently attenuated in the OE rats but not in the R rats. A 10-fold difference in serum estrogen content may mediate this. Surprisingly, serum CK activity and muscle calpain-like activity were lower (P < 0.05) in the OP rats compared with the R rats. Increases in serum insulin-like growth factor-1 content (P < 0.05) due to ovariectomy were hypothesized to account for this finding. Thus both ovariectomy and estrogen supplementation have differential effects on indexes of I/R muscle damage.

Effects of leveling agent on the uptake of reactive dyes by untreated and plasma-treated wool

Atmospheric-pressure plasma treatment of wool fabric produced a significantly higher level of adsorbed fiber-reactive dye when applied at 50 °C (pH 3.0–6.0) in the absence of any organic leveling agent. In addition, color yields indicated that dye was more uniformly adsorbed by the plasma-treated fabric compared with the untreated material. When untreated fabric was dyed in the presence of a leveling agent (Albegal B), the extent and levelness of dye sorption were enhanced. These enhancements were, however, relatively small on the plasma-treated wool compared with those on untreated wool. A ‘surface’ mechanism, similar to that proposed when plasma-treated wool is dyed in the absence of leveling agent, can explain the leveling ability of Albegal B under adsorption conditions. Increasing the dyebath temperature to 90 °C resulted in dye penetration of the fibers. Under these conditions, any enhancements of dye uptake produced by the plasma treatment, as well as the use of Albegal B, were relatively small, in contrast to the behavior at 50 °C. Improvements in the uniformity of dye sorption observed at 50 °C were, however, maintained at the higher temperature. It is concluded that the inability of reactive dyes to migrate (and so promote leveling and uniformity) once they have reacted with the fiber, means that differences in the uniformity of dye sorbed at 50 °C are still apparent at equilibrium.

Modified life cycle inventory of aluminium die casting

Aluminium die casting is a process used to transform molten aluminium material into automotive gearbox housings, wheels and electronic components, among many other uses. It is used because it is a very efficient method of achieving near net shape with the required mechanical properties. Life Cycle Assessment (LCA) is a technique used to determine the environmental impacts of a product or process. The Life Cycle Inventory (LCI) is the initial phase of an LCA and describes which emissions will occur and which raw materials are used during the life of a product or during a process. This study has improved the LCI technique by adding in manufacturing and other costs to the ISO standardised methods. Although this is not new, the novel application and allocation methods have been developed independently. The improved technique has then been applied to Aluminium High Pressure Die Casting. In applying the improved LCI to this process, the cost in monetary terms and environmental emissions have been determined for a particular component manufactured by this process. A model has been developed in association with an industry partner so this technique can be repeatedly applied and used in the prediction of costs and emissions. This has been tested with two different products. Following this, specialised LCA software modelling of the aluminium high pressure die casting process was conducted. The variations in the process have shown that each particular component will have different costs and emissions and it is not possible to generalise the process by modelling only one component. This study has concentrated on one process within die casting but the techniques developed can be used across any variations in the die casting process.

Reactive system model for building fault-tolerant distributed applications

The development of fault-tolerant computing systems is a very difficult task. Two reasons contributed to this difficulty can be described as follows. The First is that, in normal practice, fault-tolerant computing policies and mechanisms are deeply embedded into most application programs, so that these application programs cannot cope with changes in environments, policies and mechanisms. These factors may change frequently in a distributed environment, especially in a heterogeneous environment. Therefore, in order to develop better fault-tolerant systems that can cope with constant changes in environments and user requirements, it is essential to separate the fault tolerant computing policies and mechanisms in application programs. The second is, on the other hand, a number of techniques have been proposed for the construction of reliable and fault-tolerant computing systems. Many computer systems are being developed to tolerant various hardware and software failures. However, most of these systems are to be used in specific application areas, since it is extremely difficult to develop systems that can be used in general-purpose fault-tolerant computing. The motivation of this thesis is based on these two aspects. The focus of the thesis is on developing a model based on the reactive system concepts for building better fault-tolerant computing applications. The reactive system concepts are an attractive paradigm for system design, development and maintenance because it separates policies from mechanisms. The stress of the model is to provide flexible system architecture for the general-purpose fault-tolerant application development, and the model can be applied in many specific applications. With this reactive system model, we can separate fault-tolerant computing polices and mechanisms in the applications, so that the development and maintenance of fault-tolerant computing systems can be made easier.

Reactive ball milling to produce nanocrystalline ZnO

Ball milling of zinc powders in oxygen atmosphere leads to nanocrystalline ZnO. The average grain size has a value of 9 nm. The zinc oxidation proceeds gradually. It is compared with the combustion oxidation reactions of metals (Zr, Ti, Fe and Sn) reported previously. We propose a new parameter ΔH/C_p(metal) instead of simplified adiabatic temperature to judge if the mechanochemical oxidation of a particular metal happens via gradual or combustion reaction.