Monika Makowska

Interactions of n-Hexadecane with 52100 Steel Surface Under Friction Conditions

Straight-chain aliphatic hydrocarbons, particularly n-hexadecane, are used as reference fluids in research concerning the AW/EP effectiveness of triboactive additives. It is assumed, however, that under boundary lubrication conditions these apparently non-reactive hydrocarbons might influence the tribochemistry of the additives because aliphatic compounds also undergo chemical reactions. Both the thermochemical and tribochemical oxidation of aliphatic hydrocarbons lead to the formation of triboactive products (e.g. alcohols, aldehydes and carboxylic acids). Interactions of these compounds with rubbing surfaces were examined using GC/MS, XPS and EDS techniques. It has been found that carboxylic acids react with the iron surface generating salts or complex compounds.

Tribochemical Conversions of Zinc Dialkyldithiophosphate (ZDDP) Under Extremely Different Pressure Conditions

The authors performed ball-on-disk and four-ball tests. The former gave much less severe conditions than the latter. A ZDDP-containing package, blended with a mineral base oil, was tested. Completely different mechanisms of ZDDP conversions were observed. During ball-on-disk tests, ZDDP undergoes partial tribochemical decomposition. It results in a modification of the surface of test specimens—organic compounds are produced and zinc atoms diffuse into the surface. During four-ball tests, advanced structural decomposition of ZDDP takes place—S and P take part in tribochemical reactions. Probably inorganic compounds are produced, whereas there is a lack of a layer of organic ones adsorbed on the surface. The generation of inorganic compounds results from chemical reactions of decomposed ZDDP with the surface of steel specimens as well as diffusion of some elements (e.g. S) into the surface. Good antiseizure properties of such inorganic structures help to improve the tribological characteristics under severe test conditions.

Phosphorus removal in anaerobic fluidized bed reactor with active microporous filling produced by extrusion technology

Methane fermentation leads to the formation of biogas in the process of wastewater treatment, but a limitation to its use is the low effectiveness of the removal of phosphorous compounds under anaerobic conditions. The study demonstrates a method to solve this problem through the use of a magneto-active microporous filling, produced by extrusion technology from polyvinyl chloride. This has increased the effectiveness of dairy wastewater treatment by stimulating the selective development of specific groups of microorganisms and the chemical binding of the phosphorous compounds in biological processes as well as chemical sorption on the metal surface of the filling. Regardless of the used organic loading rate, the efficiency of phosphorous removal from the wastewaters was about 85%. Achieving low concentrations of phosphorous in the effluent was directly influenced by the method of the wastewater operation and disposal by magneto-active filling layer.

Lubricating Effectiveness of Secondary Metabolites from Microalgae in Different Material Systems

Microalgae, as a renewable raw material, are gaining wider technical use, due to their rapid growth and high lipid content. Thanks to their ability to produce secondary metabolites that are chemically related to vegetable oils, they can provide an alternative source of organic components of operational liquids. The study investigated the properties of the lubricating oil obtained from algae and compared them with the properties of selected commercial lubricating oils: vegetable, mineral, and synthetic. Antiwear properties were evaluated based on the value of the limiting load of wear (Goz), and antiseizure properties are based on the value of scuffing load (Pt). The studies were conducted with the use of a four-ball machine. Its test elements were 100Cr6 steel balls and the same balls with low-friction coating (WC/C). Friction tests were carried out in the following material combinations: steel-steel, steel-WC/C, WC/C-steel, and WC/C-WC/C. It was found that in the WC/C-WC/C and WC/C-steel material systems, the algae oil has better antiwear and antiseizure properties than the mineral and vegetable oil. It is therefore appropriate to consider the algae oil as a substitute for commercial oils, particularly the vegetable one for technical applications, e.g. when composing organic lubricating materials intended for the lubrication of friction systems with WC/C coatings.