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The purpose of this paper is to propose and evaluate the selection of materials for the selective laser sintering (SLS) process, which is used for low-volume production in the engineering (e.g. light weight machines, architectural modelling, high performance application, manufacturing of fuel cell, etc.), medical and many others (e.g. art and hobbies, etc.) with a keen focus on meeting customer requirements.

The work starts with understanding the optimal process parameters, an appropriate consolidation mechanism to control microstructure, and selection of appropriate materials satisfying the property requirement for specific application area that leads to optimization of materials.

Fabricating the parts using optimal process parameters, appropriate consolidation mechanism and selecting the appropriate material considering the property requirement of applications can improve part characteristics, increase acceptability, sustainability, life cycle and reliability of the SLS-fabricated parts.

The newly proposed material selection system based on properties requirement of applications has been proven, especially in cases where non-experts or student need to select SLS process materials according to the property requirement of applications. The selection of materials based on property requirement of application may be used by practitioners from not only the engineering field, medical field and many others like art and hobbies but also academics who wish to select materials of SLS process for different applications.

The use of materials in marine environments has traditionally been associated with ships. However, in recent years, important new industries have grown up which present new material problems. Notable amongst such industries are offshore oil production and desalination (production of fresh water from seawater). Also, requirements for large amounts of cooling water by modern industry have often resulted in siting of plants by the ocean, particularly in arid areas such as the Middle East. This has increased interest in the use of materials for handling seawater.

The effect of tin, copper, nickel and molybdenum on the mechanical properties and corrosion resistance of sintered stainless steel (AISI304L). The industrial use of sintered stainless steel is restricted by the poor corrosion resistance of the materials in comparison with the wrought counterpart. It has been shown in the literature that the addition of tin and copper can bring about improvements in the corrosion performance of certain alloys and this paper reports a systematic study of the use of these and other alloying additions. In this work, elemental additions of Sn, Cu, Ni and Mo singly and in combinations were made to 304L stainless steel powder. The mechanical properties and corrosion resistance to salt spray and immersion in saline solution of the sintered compacts have been measured and compared with samples made from 316L powder and wrought stainless steel. It was found that 304L containing additions of either 2% Sn or 2% Ni + 2% Cu + 1% Sn had the most improved corrosion resistance but with some loss of strength following sintering under conditions suitable for 304L powder. Increasing' the sintering time of the alloys with elemental additions from 45 minutes to two hours at 1180°C increased the strengths of the compacts to the same level as 304L and 316L while retaining the improved resistance to corrosion. ITRI Publication No. 650, is by S. K. Chatterjee, M. E. Warwick, and D. J. Maykuth, and is available from ITRI, Fraser Road, Perivale, Greenford, Middx UB6 7AQ.

This work is focused on the investigation of direct production of electrical discharge machining (EDM) electrodes through the selective laser sintering (SLS) technique using a new metal-matrix composite material made of molybdenum and a copper-nickel alloy (Mo-CuNi). The influence and optimization of the main SLS parameters on the densification behavior and porosity is experimentally studied. Additionally, EDM experiments are performed to evaluate the electrodes performance under different machining conditions. The paper aims to discuss these issues.

The new EDM electrode material used was a powder system composed of Mo and pre-alloyed CuNi. A systematic experimental methodology was designed to evaluate the effects of layer thickness, laser scan speed and hatch distance. The densification behavior, porosity and surface morphology of the samples were analyzed through microstructural and surface analysis. EDM experiments were conducted under three different regimes in order to observe the electrodes behavior and performance. The results were compared with copper powder electrodes manufactured by SLS and solid copper electrodes EDMachined under the same conditions.

The experimental results showed that the direct SLS manufacturing of composite electrodes is feasible and an adequate combination of parameters can produce parts with good quality. The laser scan speed has a great effect on the densification behavior of the samples, while the effect of hatch distance on the porosity is more visible when the overlapping degree is considered. The overlapping also had a significant effect on the surface morphology. The EDM results showed that the Mo-CuNi electrodes had superior performance to the copper powder electrodes made by SLS for all the EDM regimes applied, but inferior to those achieved with solid copper electrodes.

Significant results on the direct SLS manufacturing of a new material which has a great technological potential to be used as an EDM electrode material are presented. Valuable guidelines are given in regard to the SLS optimization of Mo-CuNi material and its performance as an EDM electrode. This work also provides a systematic methodology designed to be applied to the SLS process to produce EDM electrodes.

The increasing interest in engineering structures made from multiple materials has led to corresponding interest in technologies, which can fabricate multi‐material parts. The purpose of this paper is to further explore of the multi‐material fabrication capabilities of ultrasonic consolidation (UC).

Various combinations of materials including titanium, silver, tantalum, aluminum, molybdenum, stainless steel, nickel, copper, and MetPreg^® were ultrasonically consolidated. Some of the materials were found to be effective as an intermediate layer between difficult to join materials. Elemental boron particles were added in situ between selected materials to modify the bonding characteristics. Microstructures of deposits were studied to evaluate bond quality.

Results show evidence of good bonding between many combinations of materials, thus illustrating increasing potential for multi‐material fabrication using UC.

Multi‐material fabrication capabilities using UC and other additive manufacturing processes is a critical step towards the realization of engineering designs which make use of functional material combinations and optimization.

A review of the main metals and alloys in commercial use for resisting sea‐water corrosion

THE Mercedes‐Benz Model DB‐601A aero‐engine is a development of the Daimler‐Benz Aktiengesellschaft of Stuttgart, Germany, a firm which lias been engaged in the manufacture of automotive and aero‐engines for over fifty years. During the first World War the Daimler Motorcn Gesellschaft of Stuttgart produced the famous Mercedes aero‐engines iii three 6‐cylindcr types with ratings of 160 horse‐power, 180 horse‐power, and 260 horse‐power. Equally renowned were the 160 horse‐power and 230 horse‐power 6‐cylindcr aero‐engines built by Benz and Company in Mannheim. After the war, and as a result of the economic and financial crisis which brought almost complete stagnation to the automotive industry in Germany during the early twenties, these two companies were practically forced to combine their activities in order to survive. Accordingly in 1926 a merger was consummated between the Daimler and Benz organizations. Thus came into being the firm of Daimler‐Benz A.G. and their product, the Mercedes‐Benz line of automotive vehicles and aircraft power plants.

Amalgams, which are mechanically alloyed mixes of a liquid metal with a powder, offer advantages in situations where large devices are to be bonded to materials with significant coefficient of expansion differences or where extremely temperature‐sensitive devices are to be bonded. This is because these materials will set or harden at or near room temperature to yield hard metallic bonds with melting points from 280°C up to ∼600°C depending upon the systems used. In this paper the results of a survey study of three binary systems of gallium with copper, nickel and silver are described. Wetting characteristics, bond strengths with and without metallisation, bulk properties including electrical and thermal properties and thermal cycle performance of joints are described. The feasibility of using these materials for bonding metallised and unmetallised surfaces of a variety of ceramics and semiconductors is clearly demonstrated.

THIS paper shows briefly the origins and development of a comparatively new and certainly important branch of engineering science. For many years the alloys of the light metals, particularly of aluminium and magnesium, have been developed, until the term “light alloys” has come to be generally accepted as indicating the alloys of the light metals or any metallic alloy having a density of less than about 3·8. Towards the other end of the density scale are now being developed alloys of the heavy metals, mainly tungsten and tantalum. The techniques of production and manufacture of these two groups are very different: whereas the light alloys are produced and manipulated mainly by melting, casting, annealing, and forging, the heavy alloys are produced by various processes of powder metallurgy, resulting in substances with densities of 15 or more.

NEARLY twenty years have passed since the author had the pleasure of giving a paper on the same subject to this Society. Progress in the meantime as regards the means and art of flying has been not only sustained, but rapid, as is brought out by the simple facts contained in Table I. The amazing technology is well represented by the De Havilland Comet, which develops 460 h.p. with a weight ratio of 12 lb. per h.p. It therefore becomes interesting and perhaps useful to determine the extent to which metallurgy has contributed and is contributing.