Tuesday afternoon, 12 October

Chairmen
Professor Randall German, San Diego State University
Professor Lars NyborgChalmers University of Technology

Oral

MIM Superalloys for Automotive Applications
Kern, A (BASF SE, Ludwigshafen, Germany)

The downsizing of combustion engines in the automotive world calls for superior heat resistant materials due to the fact that charging of gasoline driven cars takes places at significantly higher temperatures (>1000 °C) compared to turbocharged diesel engines (850 °C) today. Three different Ni-base superalloys very well known as cast material in turbocharger application were developed in MIM. Specimen in the form of tensile bars were made from the MIM-materials and tested in a temperature range between 20 and 1050 °C. In addition to the comparison of measured data from tensile tests with literature values of the corresponding investment cast material, an insight into the superalloy’s microstructure and possible performance enhancement by means of heat treatment is presented.

High Temperature and Fatigue Properties of Injection Moulded Superalloy Compacts
Miura, H (Kyushu University, Fukuoka, Japan)

A Inconel 718 is one of representative Ni-base superalloys. However, it is not easy to produce the complicate shaped parts at low cost due to their poor workability. In this study, Metal Injection Molding (MIM) process, one of near net-shape forming of powders, has been applied for fabricating the Inconel 718 compacts using different type of powders; gas and water atomized powders. By optimizing the MIM process, their obtained relative density was near full density (98~99%) and the tensile property of as-sintered compacts was the strength of 1000MPa and the elongation of around 10%, which are similar to that of wrought materials. High temperature and fatigue properties of heat treated MIM compacts will be discussed in detail at the conference.

Metal Injection Moulding Process for Copper/Diamond Composites with High Thermal Conductivity by Using Nanopowder
Nishiyabu, K (Kinki University, Osaka, Japan)

High-performance heat sink has been recently required in applications of semiconductor devices such as CPU and LED. Thermal conductivity of diamond is 1000-2000 W/m¥K, which is much higher than that of copper, 370 W/m¥K. Therefore the addition of diamond particles to copper is predictably-effective in improving the thermal conductivity of sintered parts. However diamond particles are thermally-deteriorated from 500degC. The sintering temperature of conventional copper powder with a few micrometers in mean particle size is approximately 800-900deg.C. This study aims to develop the MIM process for manufacturing copper/diamond composites with high thermal conductivity. Nano-sized copper powder is used for reducing drastically the sintering temperature. In this process, the feedstock composed of nanopowder and binder was adequately prepared and it was sintered in a reductive gas atmosphere. The sintered parts were evaluated by density, SEM observation and thermal conductivity. The experimental results revealed reasonable evidences that using nanopowder could sinter at very low temperature.

Developments Of A New Generation Of Tungsten-Copper Composite Powders For MIM
Senillou, H (Eurotungstene, Grenoble, France)

Applications like heat sinks, electronic packaging, and electrical contacts require the MiM manufacture of parts combining low coefficient of thermal expansion and good thermal conductivity. Properties of tungsten-copper alloys (80:20) suit the requirements of designers. However, depending on process conditions, tungsten-copper pseudo-alloys have different chemical and physical characteristics and therefore display different final properties. A new composite (W-Cu) metal powder was developed to propose an alternative to existing solutions. It optimises both the MIM process and the thermal properties. The sintering of this new kind of powder was studied and the performance of the sintered parts was evaluated in several ways. Microstructure homogeneity, fine dispersion of copper in the tungsten network and controlled impurity levels were key points to reach a high densification and high thermal conductivity. An optimum in the size of the powder was found and high densification was achieved with a fine powder at a temperature of 1350°C while maintaining a satisfactory solid loading of the feedstock.

High Temperature Properties of MIM-Processed Superalloys
Kloeden, B (Fraunhofer Institut IFAM Dresden, Dresden, Germany)

There is a continuous demand for shifting the operating temperatures to higher values, especially in the automotive and aircraft industry, combined with the need of cost-effective mass production of the respective parts. The metal injection moulding (MIM) process offers an advantageous route for the production of large numbers of near-net-shape parts. Two Ni-based alloys (Udimet 720 and Inconel 713LC) were evaluated for their properties at elevated temperatures. These alloys contain significantly more Al (up to 6 wt%) than previously used MIM-materials. Therefore, they are able to form (gamma)’ precipitates, which lead to an increase in e.g. tensile strength at high temperatures. Furthermore, the oxidation resistance at high temperatures is ensured by the formation of an alumina passivation layer. Mechanical tests (tensile, creep) as well as the analysis of oxidation resistance were performed. The respective results will be presented and discussed with respect to possible high temperature applications.

Poster

Structure And Properties Of Carbide Alloyed Composite Manufactured With The PIM Method And Sinterhardened
Matula, G (Silesian Univ. of Technology, Gliwice, Poland)

It was fond out based on observations on the scanning microscope that the cermet structure is homogeneous with the evenly distributed carbide precipitations encompassing the high-speed steel primary grains. The main advantage of the presented experimental tool materials is the wide sintering window being only about 5°C oftentimes in case of the high-speed steels; whereas, it is about 40°C for the investigated material sintered under N2-10%H2.Introducing the carbides into the M2 steel makes using higher sintering temperatures possible, therefore, a lower sinter porosity can be attained. Moreover, carbides with the regular lattice do not get dissolved in the matrix and do not create the eutectic structure at the high sintering temperature. Quenching from sintering temperature and tempering gives the possibility to eliminate the austenitizing process. Moreover hardness increase to 70HRC after heat treatment of this materials.

Parallel Analysis Of Axial Pressing, Casting And PIM As Routes For Production Of Anisotropic ALNICO-8
Nikolic, M (Institute for Multidisciplinary Research, Beograd, Serbia)

Samples of Alnico8 were prepared from the same starting powder by pressing, casting and powder injection moulding (PIM), respectively and characterized by XRD, SEM, EDS and thermal analysis - DTA/TGA. Optimization of the sintering process was done for reaching the optimum of the energy product (BH)max for each type of samples. During sintering of the PIM specimens, special attention was paid to lowering the contents of residual C and O in the Alnico alloys since these interstitials affect the main magnetic properties. PIM samples were prepared using a feedstock composed of Alnico powder and a Catamold (BASF) binder. For optimization of the PIM samples, sintering was done in a dilatometer with coupled mass spectrometer. A sinter-HIP variant was also done. Shape anisotropy was induced by thermo magnetic treatment of all samples. Subsequently the main magnetic properties were measured and compared mutually and with the best literature results. It was clearly shown from the results obtained that PIM samples can attain the properties of Alnico samples made by classical routes.

Net-Shape Al-6061/SiC Nanocomposites By Powder Injection Moulding
Rodriguez-Arbaizar, M (University of Applied Sciences Western Switzerland, Sion, Switzerland)

Net-Shape Al6061-1vol.%SiC nanocomposites were produced by powder injection moulding. Nano-sized SiC powders were produced by inductively coupled plasma synthesis and mixed with gas atomized Al-6061powders in a high energy planetary ball mill. 2 wt.% of Sn powder was added as a sintering aid to perform a liquid phase sintering. A feedstock, containing 60 vol.% of powder and 40 vol.% of binder (low density polyethylene, paraffin wax and stearic acid), was prepared in a double sigma mixer under protective atmosphere. The green parts were first solvent debinded in a heptane bath, to remove both paraffin wax and stearic acid. Then, thermal debinding and sintering were performed in a MIM furnace, equipped with molybdenum heating elements and a debinding retort. The mechanical properties of the net-shape parts were measured by tensile tests and Vickers hardness. For comparison Al-6061 parts were also produced by the same process.

Related features for download:

• Co-sintering of functionally graded Fe2Ni/Fe2NixCr composites
• Developments in multi-component powder injection moulding of steel-ceramic compounds using green tapes for inmould label process
• Al/SiC composites with high reinforcement content prepared by PIM/pressure infiltration
• PM High Alloy Steels and PM Superalloys