The footprint of a cold spray beam has narrow dimensions and a large particle density, which lead to fast growth of deposit on precise locations. Cold spray produces compressively stressed coatings which lead to well bonded ultrathick coatings over many substrates. Since cold spray produces dense coatings with wrought-like microstructure, it can be used to produce large bulk forms. Two different bulk forms were produced: (i) ultrathick coatings strongly bonded to substrates and (ii) free standing structures (FSS). Both forms were post machined to obtain net-shape or near-net-shape articles. Bulk forms up to 60 mm were produced with many powders including metals, alloys and composites. Well bonded ultrathick coatings were produced over many substrates including aluminum, copper, SS, etc. FSS, including pipes, plates, etc, were produced by fabrication of a mandrel, spray coating bulk forms and removal of the mandrel. Coatings in the as-sprayed condition were machined and fine features such as grooves incorporated to obtain net-shape articles.

ASB Industries is involved in taking the cold spray technology from research lab into industrial applications. Cold spray programs include building a human engineered spray system, design and development of nozzles and guns capable of reliable and reproducible operation for long duration spray, process optimization for producing quality coatings at reasonable deposition efficiency and deposition rate values and preparation and characterization of coatings of industrially relevant materials. These research activities have resulted in the development of a patented ‘Advanced Cold Spray System’ with enhanced features and performance characteristics. ASB is involved in a number R&D programs to develop engineered coatings for specific customers, and a few of these applications are in various stages of commercial adaptation.

The cold spray process was used to prepare nanostructured WC-Co coatings. The coating microstructural characteristics and phase composition were analyzed via optical microscopy, SEM and XRD. The morphology and microstructure of the nanostructured WC-Co powder were also analyzed by SEM and XRD. A 10µm thick coating was achieved. The results show that there is no degradation of the WC-Co powder during the cold spray process and well-bonded and phase-pure WC coating can be produced by the cold spray process.

Oxygen-free titanium coatings are at present produced using vacuum plasma spray systems. The cold spray process can produce titanium coatings in atmospheric air at reduced cost. Variations of the deposition efficiency as well as the coating characteristics with various process parameters were studied. Results show that the deposition efficiency drops drastically below a critical temperature. The parameters which affect the jet velocity; viz., the type of gas and the nozzle geometry have maximum effect on the process deposition efficiency. Sprayed coatings were porous and exhibited a low modulus and high hardness. Post processing of the coating by machining produced dense, strong and hard coatings. Key words: Cold-Spray, Titanium, Oxidation.