Scrutinize friction improver

2019 - s friction improver 09 - 29 lubrication is the main means to reduce friction and wear. So the lubricating grease and all other lubricant is the most important performance, is its lubricity. Lubricating grease lubrication performance for: oily ( 润滑性) , abrasion resistance, 耐磨的属性) And extreme pressure property ( Extieme Presure） 。 As lubricity 'oily', one of the three kinds of performance, but it's hard to describe, is not easy to qualitative quantitative. Just like someone said 'oil' some of the more than peanut oil, soybean oil but this is just the appearance of a feeling. The author thinks that more should be reflected in its' oily 'adhesion and bridge, making it formed by the oil film can firmly adhere to the metal surface, and not easily broken; The oil film once damaged, the ability to recover and heal itself. So 'oily' is defined as a lubricant in metal surface adsorption ability. Oiliness additive added to oil, can form directional adsorption film on metal surface, so as to improve the friction performance. First, commonly used to improve the oil's lubricity vegetable oils or animal fat, so called oily agent. Later, I found some other compounds can improve oil lubricity. So, now can reduce the friction coefficient of surface friction material are collectively referred to as friction improver. Grease main effect is to reduce the friction coefficient, reducing wear and tear. Both the lubrication condition between the friction surface can be divided into fluid lubrication and mixed lubrication and boundary lubrication. Different lubrication condition of oil film thickness and friction coefficient are different. Fluid lubrication oil film thickness, boundary lubrication oil film the thinnest. Fluid lubrication minimum friction coefficient, 0. 001 - 0. 006, the friction coefficient of boundary lubrication is the largest, can be greater than zero. 5, is the most ideal state of lubrication fluid lubrication. When the friction surface contact pressure is low, high sliding velocity and friction surface completely separated by a fluid, at this point is the fluid lubrication state; Friction surface between the full oil film of certain thickness, solid friction between the friction surface to fluid friction, the friction coefficient of the size of the only depends on the size of the fluid viscosity, so it's the smallest friction coefficient, lubricating effect is best. The vast majority of lubrication state is in a state of mixed lubrication. The so-called state of fluid lubrication and boundary lubrication. In this state, the thickness of lube film with prominent surface of coordinates of each point on the micro convex body ( Relative to the surface) The maximum height of the integral mean similar, close to two metal surface, occasional metal to metal contact. To reduce the number of metal to metal contact, it is necessary to separate the two metal surfaces, keep the good fluid oil film strength. Usually need to add friction improver in oil at this time. The effect of friction improver friction improver is usually applied to boundary lubrication condition, in order to reduce the friction coefficient, improve the lubricity. Friction improver contain polar group, on the metal surface has a strong affinity. Through its polar groups strongly adsorbed on the metal surface, form a protective film to separate the metal, to prevent the direct contact, the effect of reducing friction and wear. Friction improver on the surface of the metal, belong to the physical adsorption, adsorption and physical adsorption is reversible. When the temperature increases to a certain extent, the physical adsorption film stripping. Different friction improver the stripping temperature lower limit; Usually think, fatty amines and fatty amide stripping at higher temperature. At the same time, the friction improver anti-friction effect is related to the location of the polar group; Polar groups the most suitable position is at the end of the long chain hydrocarbon, the polarity base end of the long chain of friction modifier molecule can vertically adsorbed on the metal surface, the alkyl part will be upright in oil. Such as the location of the polar group moving forward end, molecular polar group is not able to vertically adsorption, will hinder the intensive adsorption oily agent, lead to the oil film of discontinuity, not tight. In addition, the longer the hydrocarbon chain of the adsorption film thickness is, the greater the its intensity. Friction improver the variety of the latest classification of friction improver fatty acids, fatty alcohols and their salts; The commonly used fatty acids are oleic acid and stearic acid, good lubricity, the effect is remarkable. Aluminum stearate can be to prevent the occurrence of stick-slip guide under high load low speed; But its oil soluble, adverse long-term storage, has certain corrosion of metal. Lauryl alcohol such as fatty alcohol has good antifriction performance. Stearic acid ester, oleic acid glycol ester is increased with the increase of carbon chain, such as friction coefficient decreases. Dimer acid and derivatives; Dimer acid glycol ester in addition to the good lubricity, also has certain demulsibility. Fatty amines and their derivatives; Such as benzene triazole fatty amine is one who has a lubricity, antirust and oxidation resistance of friction multi-function improvement. Organic molybdenum compounds; Commonly used organic molybdenum compounds have sulfide and dialkyl phosphate molybdenum disulfide generation sulfide molybdenum dialkyl dithiocarbamate oxygen. Besides has the lubricity and good oxidation resistance and extreme pressure and anti-wear. Organic borate ester and organic borate; Phosphate ester boride has better antifriction and anti-wear. Friction improver quality control, as previously mentioned, friction improver ( Oily agent) Or 'oily' how to judge the quality of it is not easy, only through the method of indirect test; Such as determination of friction coefficient to distinguish the anti-friction performance; With hot weightlessness's ability to observe its heating stripping, with four ball machine PB value to judge the oil film to bridge and toughness, and so on. These methods must be comprehensive consideration, just have reference value.