Method for conducting micro-abrasion wear testing of materials in oscillating sliding.

Micro-abrasion is a kind of wear occurring on materials´ surfaces by action of three-body hard particles existing at the sliding interface. It is consistently reproduced by a popular laboratory method well-known as ball cratering test. Characteristically, it consists of wearing off a material sample by loading it against a ball that rotates continuously and unidirectionally under controlled conditions. A slurry containing a certain amount of hard micro-sized particles is dropped uninterruptedly onto the ball to get the particles enters the sliding contact by the ball´s rotary effect. The present method proposes a variant to the classic micro-abrasion methodology. It comprises changing the ball motion from a unidirectional to an oscillating for testing by considering new test parameters such as sliding arc lengths and frequency, which provides more realistic sliding conditions and wear rates for materials to be used in mechanical applications involving reciprocating and oscillating sliding.

Partially Deacetylated and Fibrillated Shrimp Waste-Derived Chitin as Biopolymer Emulsifier for Green Cutting Fluids-Towards a Cleaner Production.

Up to date, most metalworking fluids (MWFs) are emulsions made of petroleum-derived oil bases and sodium petroleum sulphonate emulsifiers. They are not readily biodegradable, and their waste is hazardous for users and the environment. Therefore, green MWFs are required for achieving cleaner production processes. Recently, various MWFs have been developed using vegetable oil bases to meet biodegradability to some extent. However, the emulsifier has been scarcely replaced by a green product. This research aims to produce and evaluate Pickering emulsions made of Jatropha oil (JO) and partially deacetylated and fibrillated chitin (PDFC) as emulsifiers at different concentrations. JO is a non-edible biodegradable oil with remarkable lubricity properties, while PDFC is produced by extracting chitin from waste heads and shells of the shrimp species Litopenaeus vannameii, followed by partial deacetylation and further fibrillation, which improves wettability and stabilization. The prepared emulsions were characterized in terms of creaming index and size of emulsion droplets and evaluated as MWFs in actual turning operations of AISI 1018 steel bars via minimum quantity lubrication (MQL) technique. The findings suggest PDFC as a potential eco-friendly emulsifier to form green MWFs with acceptable stability generating low cutting forces and significant workpiece finishing and chips quality.