For over 20 years UST has provided Australian industry with innovative surface engineering solutions for combating wear and corrosion. One example is our unique range of surface coating solutions for severe service hydraulic cylinders.
Hydraulic cylinders are typically chrome plated to provide protection against wear and corrosion, but chrome plating is unsuitable for use in severe corrosive environments due to the presence of numerous small micro-cracks in the coating, which allows the corrosive media to penetrate to the substrate. The corrosion at the interface between the coating and the substrate leads to coating delamination and blistering, often resulting in irreparable damage to the hydraulic system. Operating conditions where chrome plated coatings have been found wanting include hydraulic systems in harbour and ship systems (on-deck, splash zone and submerged), offshore platforms, dredges and marine mining systems and hydraulic equipment exposed to aggressive chemicals in chemical, petrochemical, steel, and paper and pulp plants.
UST has developed a range of advanced Hard Chrome Alternative Technology (HCAT) coating systems for the protection of hydraulic cylinders operating in severe operating environments, based on advanced robotic high velocity oxy-fuel (HVOF) and plasma thermal spray coatings and plasma transferred arc (PTA) hardfacing technologies. The HCAT coatings are generally advanced nickel or cobalt based ceramic-metal composite alloys, although pure ceramic coatings are sometimes used. UST makes used of advanced diamond-abrasive finishing technologies to ensure that the coatings are finished to the appropriate surface finish compatible with hydraulic seals. The HCAT coated hydraulic cylinders are able to withstand severe wear and corrosion, and certain HCAT coatings also have excellent anti-fouling or damage tolerance. The specific HCAT coating system selected depends on the specific wear and corrosion environment as well as other environmental issues (rod deflection, risk of mechanical impact, bio-fouling etc.). A further key advantage of the HCAT coating system is the ability to refurbish damaged cylinders. Because much thicker coatings are possible with thermal spray and especially PTA, hydraulic cylinders with local pitting or impact damage, or cylinders that are undersize can be refurbished without having to replace the cylinder.