Engine anti-wear repair agents usually use base oil as a carrier, and low temperature environments will significantly affect the fluidity of base oil. Under low temperature conditions, the viscosity of base oil will increase significantly, becoming more viscous and even coagulating. When the temperature drops below -20℃, the fluidity of ordinary mineral base oil will drop sharply, making it difficult for the anti-wear repair agent to be quickly transported to the surfaces of various friction parts of the engine, and it is impossible to form effective lubrication protection in time. For example, in the early morning of winter in extremely cold areas, when the vehicle is started, the engine will have a short dry friction state due to the poor fluidity of the repair agent, which will aggravate the wear of the parts. In contrast, anti-wear repair agents containing synthetic base oils can still maintain good fluidity at low temperatures. For example, products using PAO (poly alpha-olefin) synthetic base oils can still maintain a low viscosity in a -40℃ environment, ensuring that they can quickly reach the friction surface and play an anti-wear role.
The activity of various additives in engine anti-wear repair agents will be inhibited in low temperature environments. Take zinc dialkyl dithiophosphate (ZDDP) as an example. It is a common anti-wear additive. Its decomposition rate slows down at low temperatures, and it cannot quickly release active ingredients to react with the metal surface to form a protective film. Nano-scale repair materials such as nano-ceramic particles have poor dispersibility at low temperatures, are prone to agglomeration, and are difficult to be evenly distributed in the lubricant, reducing the repair effect on the worn parts of the engine. In addition, low temperatures will also affect the performance of the detergent dispersant in the anti-wear repair agent, weakening its ability to disperse impurities such as sludge and carbon deposits, making it easier for impurities to deposit inside the engine, indirectly affecting the overall performance of the anti-wear repair agent.
High temperature environments pose a severe test to the base oil of engine anti-wear repair agents. When the engine operating temperature exceeds 120°C, the base oil is very likely to undergo oxidation reactions, generating acidic substances and colloids. These oxidation products will not only reduce the lubrication performance of the base oil, but may also corrode engine parts. At the same time, high temperatures will accelerate the evaporation of the base oil, resulting in a reduction in the amount of engine oil. For example, under long-term high-speed driving or heavy-load conditions, the evaporation loss rate of ordinary mineral base oil can reach 10% - 15%, causing the concentration of the anti-wear repair agent to decrease and the anti-wear protection effect to weaken. High-quality fully synthetic base oil has better high-temperature stability, and its evaporation loss rate can be controlled within 5%, which can maintain the performance of anti-wear repair agent for a longer time in high-temperature environment.
High temperature will accelerate the decomposition of additives in anti-wear repair agent. Although anti-wear agent can quickly react with metal surface to form protective film under high temperature and high pressure conditions, excessive temperature will cause the protective film to decompose and fail prematurely. For example, when the temperature of organic molybdenum anti-wear agent exceeds 180℃, its molecular structure will break and lose its anti-wear performance. High temperature will also affect the effect of antioxidants. Some antioxidants will be consumed faster at high temperature and cannot effectively inhibit the oxidation of base oil. In addition, high temperature will cause the anti-foaming agent in anti-wear repair agent to fail. The bubbles generated by the violent stirring of lubricating oil inside the engine are difficult to eliminate. The local high temperature and pressure shock generated when the bubbles burst will destroy the anti-wear protective film and aggravate engine wear.
Some components in engine anti-wear repair agent exist in colloid form, and extreme temperature will affect its stability. In a low-temperature environment, the colloid may condense and stratify, resulting in uneven performance of the anti-wear repair agent. In a high temperature environment, the solvation layer of the colloid will become thinner, and the colloid particles are more likely to collide and aggregate with each other, which also destroys the stability of the colloid. For example, the anti-wear repair agent containing graphene nanosheets will agglomerate due to changes in surface energy at high temperatures, reducing its dispersibility and anti-wear performance in the lubricant. Therefore, high-quality anti-wear repair agents will add special stabilizers to adjust the stability of the colloid at different temperatures to ensure product performance.
Temperature directly affects the quality and speed of the anti-wear repair agent forming an anti-wear film on the metal surface of the engine. At low temperatures, the chemical reaction rate of the anti-wear agent and the metal surface is slow, the anti-wear film formation time is prolonged and the film layer is thin, making it difficult to effectively resist friction. Although the reaction rate is accelerated at high temperatures, excessively high temperatures will make the anti-wear film structure loose, and even local peeling will occur. Within a suitable temperature range (such as 80℃ - 120℃), the anti-wear repair agent can react quickly and stably with the metal surface to form a dense and tough anti-wear film. For example, within this temperature range, boron-containing anti-wear agents can form a borate protective film with the metal surface, effectively reducing the friction coefficient and wear.
To cope with different temperature environments, engine anti-wear repair agents are continuously optimized in terms of formula and technology. In terms of low-temperature performance, synthetic base oil with good low-temperature fluidity is used, and pour point depressants are added to reduce the freezing point of the base oil; for high-temperature performance, high-temperature resistant additives and base oils with excellent antioxidant properties are selected, and anti-volatile agents are added to reduce base oil evaporation. In addition, nanotechnology is used to improve the dispersibility and stability of additive particles so that they can still play a role at extreme temperatures. Some products also use intelligent temperature control technology to automatically adjust the performance of anti-wear repair agents according to changes in engine temperature, such as releasing active ingredients to improve fluidity at low temperatures, enhancing antioxidant and anti-wear capabilities at high temperatures, and improving the adaptability of products in different temperature environments.
