Pin on disc wear investigation of nitrocarburised H13 tool steel

Nitrocarburised H13 disks were tested in dry, sliding wear against a stationary ruby ball (pin). Three different 4 h nitrocarburising treatments were compared, using N2/NH3/CO2, N2/NH3/natural gas and N2/NH3 gas mixtures, resulting in compound layers of varying thickness, hardness, porosity and oxide morphology. During mild, oxidative wear, with the formation of abrasive wear debris, the most brittle and oxidised surfaces performed poorly. Polishing to a bright, reflective finish greatly reduced wear. However, the N2/NH3/CO2 sample also frequently maintained a 'very mild' wear regime, owing to the formation of a protective film between the wear surfaces, and resulting in a lowering of the friction coefficient. This treated surface was porous and covered in a complex layer of coarse oxide+epsi-carbonitride. Nitrocarburised samples and wear tracks were characterised by optical microscopy, SEM, atomic force microscopy and stylus profilometry.

Ferritic nitrocarburising of tool steels

Four different tool steel materials, P20, H13, M2 and D2, were nitrocarburised at 570°C in a fluidised bed furnace. The reactive diffusion of nitrogen and carbon into the various substrate microstructures is compared and related to the different alloy carbide distributions. The effect of carbon bearing gas (carbon dioxide, natural gas) on carbon absorption is reported, as well as its influence on compound layer growth and porosity. Partial reduction of Fe3O4 at the surface resulted in the formation of a complex, epsi-nitride containing oxide layer. In H13, carbon was deeply absorbed throughout the entire diffusion zone, affecting the growth of grain boundary cementite, nitrogen diffusivity and the sharpness of the compound layer: diffusion zone interface. When natural gas was used, carbon became highly concentrated in the compound layer, while surface decarburisation occurred with carbon dioxide. These microstructural effects are discussed in relation to hardness profiles, and compound layer hardness and ductility. The surfaces were characterised using glow discharge optical emission spectroscopy, optical and scanning electron microscopy and X-ray diffraction.

Models of scientific community: Charles Sanders Peirce to Thomas Kuhn

Scientific community' is common currency in the study of science, largely due to Kuhn's use of the term in his highly influential book The Structure of Scientific Revolutions. As this article explains, however, 'scientific community' was not of Kuhn's coining. It was hinted at by Peirce, and expressly designated by Royce. On a few occasions Fleck affirmed a scientific community, while Polanyi studied it in some detail. The article concludes by comparing these thinkers' 'communitarian' interpretations of science.

Damping properties of open cell microcellular pure Al foams

Damping behaviours of the open cell microcellular pure Al foams fabricated by sintering and dissolution process with the relative density of 0·31-0·42 and the pore size of 112-325 μm were investigated. The damping characterisation was conducted on a multifunction internal friction apparatus. The internal friction (IF) was measured at frequencies of 1·0, 3·0 and 6·0 Hz over the temperature range of 298-725 K. The measured IF shows that the open cell pure Al foam has a damping capacity that is enhanced in comparison with pure Al. At a lower temperature (∼400 K), the IF of the open cell pure Al foams increases with decreasing relative density, with decreasing pore size and with increasing frequency. The IF peak was found at the temperature range of 433-593 K in the IF curves. It is clear that the IF peak is relaxational type and the activation energy associated with the IF peak is about 1·60 ± 0·02 eV. Defect effects can be used to interpret the damping mechanisms.

Microstructural evolution during hot deformation of duplex stainless steel

The microstructure evolution during hot deformation of a 23Cr-5Ni-3Mo duplex stainless steel was investigated in torsion. The presence of a soft δ ferrite phase in the vicinity of austenite caused strain partitioning, with accommodation of more strain in the δ ferrite. Furthermore, owing to the limited number of austenite/austenite grain boundaries, the kinetics of dynamic recrystallisation (DRX) in austenite was very slow. The first DRX grains in the austenite phase formed at a strain beyond the peak and proceeded to <15% of the microstructure at the rupture strain of the sample. On the other hand, the microstructure evolution in δ ferrite started by formation of low angle grain boundaries at low strains and the density of these boundaries increased with increasing strain. There was clear evidence of continuous dynamic recrystallisation in this phase at strains beyond the peak. However, in the δ ferrite phase at high strains, most grains consisted of δ/δ and δ/γ boundaries.

Dynamic adjustment of ferrite grains during dynamic strain induced transformation

The dynamic adjustment of ferrite grains formed during 'dynamic strain induced transformation (DSIT)' is an important feature of this mechanism that has not been addressed previously. A novel experimental method was applied to follow the effect of deformation at different stages on ferrite formed initially through DSIT. It is shown that while the continuous dynamic recrystallisation (CDRX) appears to be an acceptable mechanism for re-refinement of coarser grain size (i.e. dα>2dDSIT), it cannot explain the steady state grain size for finer ferrite grains (i.e. dα<2dDSIT). Other potential mechanisms involved in this phenomenon are examined.

A conceptual matrix model for biological data processing

This paper proposes a conceptual matrix model with algorithms for biological data processing. The required elements for constructing a matrix model are discussed. The representative matrix-based methods and algorithms which have potentials in biological data processing are presented / proposed. Some application cases of the model in biological data processing are studied, which show the applicability of this model in various kinds of biological data processing. This conceptual model established a framework within which biological data processing and mining could be conducted. The model is also heuristic to other applications.

Exodus of 'mineral rights' from the South African Mineral Law

Transformation of the mineral law system as part of the new political  dispensation in South Africa has long been foreseen. Subsequent to a Green and White Paper, as policy documents, the Department of Minerals and Energy published a Mineral Development Draft 8il12000 for public comment. This eventually culminated in the acceptance by Parliament of the Minerals and Petroleum Resources Development Act 28 of 2002, which came into operation on 1 May 2004. The Act will transform thE! mineral law system and the mining industry in" general. In this article the phaSing-out by the Act of the historical notion of 'mineral right' is examined. It is argue..d that the Act will lead to an exodus of the notion of mineral rights and will replace It with less secure prospecting rights and mining rights which, albeit real in nature, will depend on compliance with provisions of the Act and the exercise of discre.Von by the Minister.

Nature of new order rights to minerals : a rubikian exercise since passing the mayday rubicon with a cubic zirconium?

The Mineral and Petroleum Resources Development Act 28 of 2002 has created new categories of rights to "minerals" that may be granted to applicants by the Minister of Minerals and Energy. In this article the nature of these rights will be examined. The legislature has labelled prospecting rights and mining rights to minerals as limited real rights in the MPRD Act. The remaining rights to minerals are not labelled. Provision is made for registration or recording rights in the revived Mining Titles Registration Act 16 of 1967 (as amended). Registered rights are claimed to constitute a limited real right binding against third parties. Discrepancies and contradictions regarding the nature of rights to minerals are created by the two statutes. It is concluded that only upon clarification of the provisions of the two sister statutes, would the nature of rights to minerals be more evident. The proposed amendment of section 5(1) of the MPRD Act would be in line with property doctrine based upon the common law and is to be welcomed.

Entrepreneurship in Mexico : lessons for stakeholders in New Zealand

A “neighbour” separated by 6,000 km of Pacific, Mexico is by far New Zealand’s largest trading partner in Latin America and its 15th largest overall. With two-way trade worth NZ$584 million in 2002, many Mexicans grow up on New Zealand milk powder and baby formula. Not only is Mexico’s population of 100 million a huge potential economic partner in its own right, through its network of free trade agreements, Mexico has preferential access to 860 million consumers in 32 countries covering sixty percent of the world’s GDP.

Like New Zealand, Mexico is a “New World” country open to new ideas and innovation. Also like New Zealand, Mexico is known internationally for economic reforms that have created two outward-looking, world-trading, and competitive economies. During the last 50 years, the Mexican economy has shifted away from the once dominant sectors of agriculture and mining toward more industrial activities, especially in the major urban centres of Mexico City, Monterrey, Guadalajara, and other regional centres, where entrepreneurs are concentrated. With this shift, a new class of entrepreneurs arose with the support of the government.

One of those regional centres is the State of Sinaloa, with its capital city, Culiacán. Spearheaded by a visionary government and personified by the Secretary of Economic Development, Heriberto Felix Guerra. Secretary Felix is himself restaurant entrepreneur who owns a growing chain of “concept food” restaurants in the region.

It is no accident that when New Zealand Prime Minister Helen Clark visited Mexican President Vicente Fox Quesada on 15 November 2001, one of the topics of conversation was the fact that very day their two countries had been benchmarked as two of the world’s most entrepreneurial countries in the Global Entrepreneurship Monitor 2001 survey.

More germane, both countries have low-aspiration entrepreneurs who generate low levels of wealth and have low potential for growth. Both are dominated by micro-businesses that do not have high-value-added components and are not investment-ready and pre-qualified for risk capita.

This leads to the question, what can New Zealanders learn from the experience of Mexican entrepreneurship?

Effect of transformation mechanism (static or dynamic) on final ferrite grain size

A simple series of test was developed to highlight and compare the difference between the static strain induced transformation (SSIT) and the dynamic strain induced transformation (DSIT) mechanism in grain refinement and also to investigate the origin of the difference between the two mechanisms. The results showed that while the SSIT sets up a two-dimensional impingement among the ferrite grains, it cannot avoid their coarsening (normal growth). However, the DSIT forms a group of grains with a three-dimensional impingement which does not coarsen and maintains their fine size throughout the transformation, thereby, reduces the final average grain size.

Parameter sensitivity analysis of surface plasmon resonance biosensor through numerical simulation

Surface based analytical tools have gained more importance for rapid, sensitive and label-free monitoring of molecular recognition events. Surface plasmon resonance (SPR) has played a prominent role in real time monitoring of surface binding events. SPR is increasing its significance especially for the study of ultrathin dielectric layer. This paper investigates the role of thin films of gold, silver and aluminium for protein detection in SPR biosensors. It is shown that the sensitivity, which is indicated by the shift of plasmon dip, is not linearly related to the thickness of protein but quadratic over a specific range. The approach involves a plot of a reflectivity curve as a function of the angle of incidence.