Densification and Deformation Behavior of Sintered P/M Zinc-Zinc Oxide Composite during Cold Upsetting
Studies were carried out to evaluate the initially preformed density and initial aspect ratio on the densification behavior of sintered Zinc and Zinc Oxide composite. The preform possessed 0.85 is the initial density. Aspect ratio for three different oxidizing temperatures (at 150°C, 200°C and 250°C) varied from 0.4 to 0.85. Properties of Zinc-Zinc Oxide composites with respect to linear strain, lateral strain and true stress were evaluated and plotted. Studies revealed that higher stress and higher strain values are obtained in composite when compared to the Zinc dust. The composite of Zinc-Zinc Oxide obtained at 150 o C possessed the highest stress and strain when compared to the composites obtained at others two temperatures (200 o C and 250 o C).
P/M industry trends new technologies propel P/M growth
The P/M industry enjoyed continued growth in 1995 but not at the high-pressure pace of the previous three years. Processes such as warm forming, spray forming, isostatic pressing, and metal injection molding will grow into the next century along with the use of P/M superalloys, high-speed steels, advanced particulate materials and iron and stainless steel powders. P/M is being adapted increasingly into new products as properties improve.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.