Since the advent of nanomaterials, researchers have attracted widespread attention in many fields because of their unique properties. In the field of lubrication, studies have found that nano-carbonates have good anti-wear effects. The carbonates used in the current research mainly include CaCO3, MgCO3, BaCO3, Na2CO3, etc. Considering environmental friendliness, preparation cost, performance and other factors, nano-CaCO3 is widely used in the lubrication field.
1. Application of nano calcium carbonate in the field of lubrication
With the enhancement of people’s awareness of environmental protection and the improvement of environmental protection laws and regulations, green and environmentally friendly nano-lubricating additives are more and more popular. Nano-calcium carbonate particles do not corrode metals and do not pollute the environment, so they are a promising lubricating additive. Therefore, more and more researchers have investigated its application performance in the lubrication system. In general, the application of nano-calcium carbonate in the field of lubricating oil is mainly reflected in three aspects: high-alkaline metal detergent, grease thickener (especially in high-basic complex calcium sulfonate-based grease) , Efficient extreme pressure antiwear agent.
1.1 Overbased Metal Detergents
The earliest application of nano-calcium carbonate in the field of lubrication is the preparation of overbased metal detergents. In the 1950s, because high-power supercharged diesel engines and marine diesel engines burned high-sulfur fuels, in order to solve the problems of increased carbon deposits on pistons and corrosion of cylinder liners, people began to develop Overbased metal detergent for metal content in salt. Highly basic metal detergents must meet the following conditions: strong alkalinity; good stability after reacting with acid; no adverse effects on oil products after reaction; good fluidity; transparent, stable, and good oil solubility ; cheap. Only the inorganic carbonate colloidal system meets these conditions, and calcium salts are developing rapidly among the currently used carbonates.
1.2 Thickener for grease
Nano-calcium carbonate, as a thickener for grease, is in the research and development stage, and is currently mainly used in complex calcium sulfonate-based greases. Composite calcium sulfonate-based grease has excellent high and low temperature performance (dropping point greater than 330 ℃), mechanical stability, colloidal stability, oxidation stability, corrosion resistance, water resistance, excellent rust resistance and extreme pressure and anti-wear It is known as “a new generation of high-efficiency grease”, which can be used as a general-purpose grease to replace the current calcium-based, sodium-based, lithium-based and aluminum-based greases. Its application has been extended to steel, smelting, power generation, shipping, railways , automobiles, construction, food machinery and other fields.
1.3 Efficient extreme pressure antiwear agent
The current application and research of extreme pressure antiwear agents can be divided into extreme pressure antiwear agents containing sulfur, phosphorus and chlorine, organometallic salts, and extreme pressure antiwear agents such as borates and rare earths developed for environmental protection. agent. During the development of environmental protection anti-wear agents, it was found that sulfonate has certain anti-wear ability. As an inert extreme pressure agent, sulfonate can reduce friction, prevent sintering, and neutralize acid pollutants. It produces corrosion without causing environmental pollution. It is a kind of extreme pressure antiwear agent with development prospects. At present, people have treated such extreme pressure and antiwear agents by boriding, vulcanizing and other methods to improve their extreme pressure and antiwear properties.
Nano-calcium carbonate is one of the green and environmental-friendly nano-lubricating additives. More and more scholars have studied its application performance in high-alkaline metal detergents, grease thickeners and high-efficiency extreme pressure anti-wear agents. After analysis, it is found that the crystal form, particle size and shape of nano-calcium carbonate have an impact on its lubricating performance. For example, in overbasic metal detergents, the important problem to be solved is the particle size control of nano-calcium carbonate; In terms of thickener, it is necessary to control the particle size, crystal form and shape of nano-calcium carbonate; in terms of high-efficiency extreme pressure and antiwear agents, its crystal form has a great influence on the extreme pressure performance of sulfonate. Therefore, the controllable preparation of nano calcium carbonate is particularly important.