In this paper a documentation was made to highlight the characteristics obtained on surface modifications by means of the Cold Spray, using different powders based on tungsten carbide (WC) and agglomerated with nickel, sprayed on different materials, as well as the possibility of using 52100 steel, which is often used in the manufacture of rolling bearings and which has acquired high performances both in terms of wear and fatigue and in terms of high resistance due to the alloying with chromium and the high percentage of carbon. Studies on the use of WIP-C1 powders, powders attributed exclusively to the cold spraying process, and the prior use of WIP-BC1 powders, intended to establish a stronger bond between the substrate and the base layer, have shown that good wear and impact resistance is obtained and the risk of delamination and interfacial porosity has been minimised. Studies with different coating compositions using several methods to improve surface quality by surface spraying, namely HVOF (high velocity oxygen fuel), CGDS (cold gas dynamic sterilization) and CS (cold spray), led to an improvement in performance, with the cold spray process showing improved scratch resistance, good adhesion between the substrate and the sprayed layer and higher hardness. Surface spraying is an efficient process to obtain additional characteristics, improving mechanical, tribological, corrosion and erosion properties, and of all the other techniques, Cold Spray becomes competitive because it is the only technology that deposits particles below the melting point.

According to Eurostat in 2018, Romania occupies the penultimate place in waste recycling. Packaging waste, generated in the European Union, was 174 kg per capita, but these quantities varied between Croatia - 67.8 kg per capita and Germany - 227.5 kg per capita. In the first place are waste paper and cardboard - 41%, plastic - 19%, glass - 18%, wood - 16% and metal - 6%, in the European Union 2018, these types being the most common household waste. Of the types of packaging waste, glass with 18.7%, is the greatest danger to the environment, being a waste that is not biodegradable, obtained by melting a mixture of quartz sand, limestone and soda ash. Glass packaging waste is 100% recyclable, theoretically, if the recycling and sorting process is followed, removing impurities (paper, sand, metals, etc.), non-compliance with the process will make the smelting process impractical. By recycling one ton of glass, we save 660 kg of sand, water for four people a day and avoid emitting 315 kg of carbon emissions from the greenhouse. Glass packaging waste is recycled with various professional equipment, which is used to obtain glass granules of different sizes, from 0.1 mm to 10 mm, the edges of the granules are rounded and have the appearance of fine sand. The present study presents the use of sand obtained from recycled and crushed household glass, in constructions, filters for domestic water, thermal insulation. The sand obtained from the recycling of household glass has a great advantage, it can be used cold and hot, temperatures weighing 1000C °, substantially reducing production costs, higher resistance by up to 30% and processing time.