On the thermo-mechanical events during friction surfacing of high speed steels
This paper is concerned with the friction surfacing of high-speed steels, BM2, BT15 and ASP30 onto plain carbon steel plate. The events that the matrix and carbides experience as the coating material pass from the coating rod to the substrate, in forming the coating, is described. The coating is observed to harden automatically within a few seconds of being deposited onto the cold substrate. This autohardening is observed to be an inherent feature of the friction surfacing process and the only post-coating heat treatment required is tempering, as with traditionally hardened high-speed steels. The mechanism of autohardening is discussed in terms of the mechtrode/coating/substrate thermal system.
Effect of process parameters during friction coating on properties of non-dilution coating layers
AbstractFew surface modification processes appear to coat a 1 mm thick compact layer on a substrate successfully, although several technologies have been proposed and applied. The present paper concerns a fundamental approach to establishing a friction surfacing technique that produces a 1mm thick hard coat. Experiments were carried out to clarify the effect of process parameters on the quality of coatings. Martensitic stainless steel with 1C-17 Cr was the coating material and low carbon structural steel the substrate, using a conventional friction welding machine equipped with a sliding stage. A 20 mm wide and 1 mm thick stable hardened layer was produced using a 20 mm dia. Rod of coating material. The dimensions of the layer depend on the rotational speed of the consumable rod, as lower rotational speeds produce thicker, wider coating layers. Calorimetric measurements revealed that the total heat input rate was not influenced by the frictional speed, however the ratio of thermal distributions on to the ...
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.