Friction and wear characteristics of organic thiophosphoro derivatives — a critical appraisal

Abstract

The friction‐ and wear‐reducing characteristics of a number of oil soluble sulphurised and phosphosulphurised derivatives for automotive and industrial applications have been reviewed. A critical appraisal of the suggested causes and mechanism of friction reduction and antiwear characteristics has been made. A review of the investigations carried out so far indicates that the creation of in situ films of simple inorganic salts, such as molybdenum disulphide, iron sulphide or phosphates of low shear strength and lamellar structures, does not appear to be the primary cause of low friction and wear. The authors have, therefore, undertaken a programme to synthesise and study the chemistry and tribochemical reactions in relation to friction and wear characteristics of hydrocarbon‐soluble thiophosphoro derivatives of alkyl phenol, alcohols and fatty esters, in order to establish relationships between the reactivity, chemical nature and crystal structure of films formed on rubbing surfaces, and antifriction and antiwear characteristics. Molybdenum salts of various phosphorothio derivatives of pentadecylphenol and lauryl oleate of specific structures have been synthesised, and the friction and wear properties of their blends in mineral oil base stock have been studied. It can be clearly inferred from the results that type of bonding between sulphur, phosphorus and molybdenum, and reactivity of these derivatives with rubbing surfaces, determine their friction‐reducing and antiwear characteristics. Their reactivity with iron and the nature of films formed are under investigation.

Anti wear and anti friction characteristics of tribochemical films of alkyl octa-decenoates and their derivatives

“…Most of these films show much better antiwear characteristics because these are low energy surfaces and possess higher shearbility than the corresponding metallic and inorganic oxide sulfide and phosphorous based complexes. The antifriction properties observed in some of these chemisorbed organic films are due to sandwich like structures [24] formed by poly-quinones and hydroxy-aromatic derivatives with chemically bound iron which form layered structures easily slipping over each other, thus giving rise to lower friction coefficients. The structural characteristics of these films and the manner in which these films are formed are thus are intimately related to their antiwear and antifriction properties.…”

“…• Analytical studies of surface films involving various tool such as SEM, AES, LEED and X-ray photo electron spectroscopy which gives relative abundance of elements in surface films, the structure of surface films and the radicals generated at the surface [1, 4-6, 15, 30-37]. • Studies of reaction products of iron with additives and the study of the soluble reaction products in bulk of the hydrocarbon medium [3,9,12,14,20,[22][23][24][38][39][40][41].…”

“…These studies lead to no clear correlation of the structural characteristics of the additives [24][25][26][27], the extent of surface reaction, the quantities and quality of chemisorbed films formed on the surface with regards to their antiwear and antifriction properties. Godfrey [35] has distinctly shown that iron sulfides or oxides do not posses properties such as low shear strength, plasticity, good basal cleavage and low melting point, which are considered to be important characteristics for low wear and friction properties under boundary conditions.…”

Triton B Mediated One-Pot Synthesis of Thiocarbonic Ester Derivatives in Non-Aqueous Medium

“…Trithiocarbonic acids and their derivative esters comprise of vital class of compounds for various industrial, synthetic and medicinal applications.They are extensively used in various aspects as additives, lubricating oils [1][2][3], pesticides, vulcanization promoters, stabilizers and polymeric composition additives [4]. Their derivatives are used in reversible and addition fragmentation in chain transfer [5].…”

“…Their derivatives are used in reversible and addition fragmentation in chain transfer [5]. They have been popularly used as pesticides, insectides [2], protective group [3], pharmaceuticals [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], medicinal chemistry [5,[20][21][22][23] and as a active linkers in organic synthesis [24,25]. Some of the conventional methods was used for the synthesis of thiocarbonic acid esters with thiophosgene [26], chlorodithioformate [4] and their derivatives with carbon monoxide [21].…”