Search results

In the production and overhaul of aero engines chemical and electrolytic surface treatment processes such as electrolytic degreasing, chemical and electrochemical etching, chemical descaling and chemical stripping of thermally sprayed coatings are used. In the course of some of these processes the heat resistant nickel and cobalt base alloys found in the “hot end” of the newer gas turbines are attacked. These superalloys have a common characteristic, namely, they are precipitation hardened. The alloying elements added for this purpose give rise to intermetallic compounds (carbides, nitrides, carbonitrides) which appear as inclusions of various shapes and sizes within the grain or at the grain boundaries. The conclusion from this work is that these intermetallics present as separate phases can be dissolved out by oxidative attack leaving pits. The separate processes and their objectives are detailed. It is shown in which process stages and in which solutions attack occurs. The inclusions have been analysed and the nature of the attack is illustrated. We conclude from this work, which has embraced seven nickel and cobalt base materials, that certain processes or process steps cannot be permitted on these alloys. For cleaning and etching alternative processes are given. For descaling a new compatible process was evaluated and will be discussed in a second report.

SAFETY is uppermost in the minds of all who travel by sea, and the use of reliable materials and methods of boat construction is essential in establishing confidence. The use of fasteners which can perform their function without seizing or deterioration by corrosion over long periods of service goes a long way towards obtaining the desired standard of performance.

Describes the efforts made by Newcastle Breweries to improve its competitiveness by implementing TQM and therefore achieving superior customer satisfaction. Follows the company through its introduction of a “quality customer package” outlining the range of services available to the customer; the creation of time for open forum discussions; involvement of all employees; and the implementation of its quality council, quality improvement teams and “bright ideas” suggestion scheme. Shows that the latter, with its rewards for employee initiatives, and other new ideas, such as “a day in the life” appreciation courses, have significantly changed the company′s culture.

The purpose of this study is to develop a moderated mediation model by which quality-oriented product design practices influence operational performance via supplier involvement under the different levels of product modularity.

The authors use the multisource data from 268 manufacturing firms worldwide and apply regression and the PROCESS macro model to test the moderated mediation model.

The findings reveal that quality-oriented product design practices enhance operational performance directly and do so indirectly through promoting supplier involvement in quality improvement. In addition, this indirect effect is stronger when the level of product modularity is high.

By exploring the interaction effects of quality-oriented product design and product modularity, this study provides valuable insights into the ways in which manufacturing firms improve operational performance more effectively.

Changes at the top for STN International. After 15 years as the Scientific Directorof FIZ Karlsruhe, Dr Werner Rittberger will step down at the end of this month. Taking up the post will be Professor Georg Schultheiss, a nuclear engineer by training.

Turbine blades in gas turbine engines operate at elevated temperatures and in highly oxidising atmospheres that can be contaminated with fuel residues and sea water salts. These components, which are expensive to produce, are subjected to high stresses during operation but must be totally reliable during their design life. An economic way to maintain blade properties is to coat the base metal superalloy with a protective layer capable of resisting both high temperature oxidation and hot corrosion. Conventional aluminide coatings are widely used for this purpose but platinum aluminides offer improved corrosion resistance. A collaborative exercise involving Rolls‐Royce and Johnson Matthey has now resulted in the development of a platinum aluminide diffusion coating that offers some advantages over the commercial systems.

Levels of selected essential metals (Cu, Fe and Zn) and non‐essential metals (Cd and Pb) were determined by the wet digestion based atomic absorption flame spectrophotometric method in twenty canned foodstuffs of local and foreign origin. The study revealed that on average, the concentrations of Fe, Cd and Pb in local foodstuff were more than those found in imported canned products. The contents of Fe and Pb in local canned food were almost double that of the counterpart imported versions. Analysis of the construction materials of the tins indicated that some metals, such as Pb, had levels twice as high as those found in the foreign tin containers. The results showed that the Cu concentration in various foodstuffs ranged between 0.04 and 8.88mg/kg, Fe between 3.07 and 126mg/kg, Zn between 0.19 and 22.8mg/kg, Cd between 0.15 and 1.16mg/kg and Pb between 0.11 and 2.04mg/kg. The results are compared with the levels of metals in corresponding data from the literature.

The paper aims to examine the enrichment of Cu, and the type of attack occurring during the dissolution of Al‐3.84%Cu alloy in 0.5 M NaCl.

The approach is to use scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDX) and solution analyses using atomic absorption spectrophotometry.

Examination of the surface after five days of immersion showed that Cu clusters had concentrated around the edges of the specimens and two types of localized corrosion were evident, pitting corrosion and the intergranular attack, which were concentrated mainly around the Cu clusters and in the regions where a higher concentration of Cu was evident. After 80 days of immersion, the higher concentration of Cu was distributed over nearly the entire surface and its concentration differed from one site to another.

The analysis results of the study confirmed the mechanism of simultaneous dissolution.