触点润滑剂工作原理及实际使用效果

触点润滑剂工作原理及实际使用效果 Working principle and practical effect of contact lubricant Electric switch electric contact is one of the important parts of the electrical contact system, this article through to the contact failure factors and the failure mechanism analysis, discusses in detail contact protection and lubrication technology, to improve the reliability of the electrical contact point effect and improve the mechanism, and puts forward the contact principle of the selection and use of lubricant. Factors affecting the flux of the current in the contact surface In understanding contact lubricants to improve the mechanism of the electrical contact properties before, must first understand the following influence between the contact surface current flux of several main factors. The contamination of the contact itself Normally, contact is work in an airtight or unsealed environment. The contact work is in an unsealed environment, because air contains different kinds of pollutants, so that the exposed metal surface will inevitably be contaminated by different levels. Even work in contact in a sealed environment, due to its characteristics of working medium can also decompose release different content and nature of the organic gas, therefore also cause pollution of different degrees of contact surface. The direct harm of the contamination on the surface of the contact surface is the apparent increase in contact resistance of the contact surface of the contact surface. In order to make the electrical contact system that is carrying the load work properly, the protective film must be removed effectively. The arc corrosion of the contact In an electrical contact system, when the contact is closed or the load is turned on, the power of the switch unit, which is about a unit of magnitude more than 1A, usually occurs in an arc. Due to arc discharge contact surface causes the moment of local high temperature, melting, gasification and deformation of metal surface caused by, at the same time, still can make in the air or electric contact system internal gas pollution of impurities in the metal surface, and form a layer of organic or inorganic membrane. The arc discharge phenomenon causes the contact surface of contact surface to increase. Arc discharge will be in the contact surface between the electrochemical reaction and produce nitric acid in the air, first in contact surface corrosion membrane, and then form a layer of conductive metal compounds. Contact surface between the air in the arc discharge under the action of the ionization and ionization produced after high temperature, at the same time with the contact surface between the metal ion "migration" phenomenon. This type of electrochemical phenomenon is especially prominent in the process of carrying out direct current. The main surface of the "migration" caused by the arc discharge is the "pointed head" and "crater" arc of the crater. Here should be particularly pointed out that: in addition to the above contact load flow density is the cause of arc discharge, the contact surface degree of finish is also the cause of arc discharge. Whether fixed or not fixed contact, because the two contact surfaces between the rough caused by arc discharge, also can make contact surface corrosion prematurely by arc discharge. In the corrosion of arc light discharge, the damage of the resistance load to the contact is minimal. Because the resistance load is relatively fixed, the contact is not affected by the pulsations when the load flow is carried out. And inductive load (such as motor, etc.) in the starting when the starting current is nearly 10 times the normal working current, make contact in the current density change of current-carrying work, by the arc discharge of corrosion damage is greater. The rapid increase in the current density also increases the heat of the contact, causing the arc to corrode and melt the surface of the contact surface more seriously. For capacitive loads, such as tungsten, it has the same starting current as the perceptual load, and how to protect the contact points must be taken seriously. In terms of the above discussion, people who work for current carrying electric contact system, if it work environment corrosion, arc discharge, when designing electric contact system must pay special attention to, and take the necessary measures to make the arc discharge corrosion control to a minimum. Mechanical wear corrosion between contact surfaces It is well known that neither the chemical coating nor the mechanical process can make the surface absolutely smooth and smooth. The occurrence of wear and tear between contacts will be inevitable. The touch itself bounces back Any kind of mechanical structure of electric contact system, because of its mechanical properties, contact in finish load conversion work will inevitably accompanied by contact rebound phenomenon. In practical application, electric contact system are working in a state of frequent startup and shutdown, this not only increases the contact back to jump frequency, but also accelerated the contact of the wear and tear. More serious harm is every rebound of contact may cause arc discharge, closed with the near contact surface and discharge intensity is bigger and bigger, and the duration of the longer and longer. When the electrical contact system works in an inductive or capacitive load environment, the damage caused by the contact bounce can be particularly severe. The contact bounce not only causes the surface of the contact to reheat but also suffers high energy arc damage, and it also increases the likelihood of corrosion and melting. Contact rebound on in addition to its own electrical contact system of other hazards are often ignored, however, with the continuous development of science and technology, more and more strict with the reliability of the automatic control system, so the contact back to jump a pulsating current impact caused the damage to the control circuit engineers pay more attention to. In precision electronic measuring instrument, on the other hand, due to the contact rebound makes the control circuit can't cleanly opening and closing is detected object, so this will jump can result in instrument appear false readings or error measurement results are obtained. The touchpoint actually USES microvibration in the environment The so-called microvibration wear refers to a small amount of contact motion, which is generally within a range of tens of microns to a hundred micrometers. The main reasons for the microvibration are the following: temperature changes; Electromagnetic induction vibration; Acoustic vibration. In this regard, experts in Europe and the United States have conducted more in-depth studies. Micro vibration phenomenon is bound to produce the "migration" and the wear of metals, when the contact surface due to wear or debris and cause further corrosion of ground fall, according to a process for friction corrosion. For different materials, the resulting wear and tear of microvibration is different. Common contact materials - gold, for example, because of its chemical properties relative stability, and gilded the contact surface of the metal in general will only after micro vibration abrasion and aggravate the wear debris. However, the corrosion of the base material caused by the gold-plated porosity should be paid attention to. In general, other contact materials such as copper, tin, silver or such alloys will be corroded by friction other than gold. When the metal material of different hardness is applied, the friction corrosion is aggravated by the single tendency of the phenomenon of metal "migration". For the platinum group elements and their alloys, the latest research shows that because of platinum and platinum alloy catalyst will make contact surface covering a layer of fairly thick and difficult to remove organic polymers, so that the contact surface of contact resistance increase greatly. How the touch lubricant works The effect of the contact lubricant on the corrosion of the contact itself Often, attention is focused on the processing and protection of the coating, while neglecting to focus on the pore. The most typical example of a practical application is the gilded point, which is widely held to be that the gold-plated contact surface is not oxidized and can be treated without lubrication. This is also a very wrong idea. There is an existing discussion about the damage caused by the porosity of electroplating, but the improvement of the coating performance is necessary. On the coating surface coated with the right amount of lubricant, can fully fill the gap, and effectively prevent moisture through coating, metal coating substrates from oxidation corrosion; And lubricants have certain affinity for metallic coating, can form a more tenacious film. So the improvement of the lubricant on the surface electroplating performance of the contact surface is mainly shown in: A: effectively increase the bonding strength of the electric coating B: effectively improve the oxidation and wear resistance of electroplating. The improvement of the electric arc corrosion between contacts A lot of experimental research has proven to work contact lubricant with similar characteristics of the semiconductor, the space between the contact surface is filled with lubricant effectively makes can greatly increase the contact area, combined with the lubricant also allows an electric current passes through, so the lubricant can prevent the contact surface in the space between the arc discharge phenomenon, and can expand the electric contact area, to reduce the contact resistance and reduce hair hot spots. Open circuit for electric contact system arc discharge between the contact surface corrosion, contact lubricant oil by bridge principle (quantum tunnel effect) to prevent the generation of arc discharge. In terms of the improvement mechanism, contact when disconnected, lubricants can bridge between two contact surfaces in the formation of oil (quantum tunnel), and the current can flow through oil bridge, so the arc discharge effectively restrain; Contact when closed, the contact surface of the lubricating oil film will take the lead in merging to form oil bridge, thus the potential difference between the two contact surfaces after falling rapidly make arc discharge is effectively suppressed. Even if the arc discharge occurs occasionally, it is only the lubricating film, not the metal surface. The contact lubrication technology can greatly reduce the damage of arc discharge, and greatly improve the reliability of the electrical contact system. And years of practical experience have proved that. The results of the improvement of the contact surface wear and the surface arc of the contact surface are reflected in the actual use of the contact. The improvement of mechanical wear and tear on the contact surface of contact lubricant Reasonable use of lubricant can greatly reduce or prevent the wear and tear on the surface of the contact. In terms of improving wear mechanisms, on the one hand, lubricant can effectively fill the cavity of the contact surface, thus in the contact surface to form a complete applying a film, the lubricant oil film can greatly reduce the friction. On the other hand, the oil film can protect the surface of the friction from further oxidation and corrosion. In general, the proper use of lubricants can also greatly reduce the impact of vibration wear and friction. Must remind the attention of engineers here is: due to the contact surface of the speed and degree of wear and tear, respectively, and the working frequency of contact switch, the combination form of contact, contact surface roughness, contact surface of the material, the contact surface contact pressure and contact surface of the working temperature and other factors, so in choosing types of lubricants, want to combine the actual working environment, choose to adopt quality lubricant oil lubricant or grease. The choice of lubricants is discussed in detail below. The improvement in the bounce of the contact itself The rebounces can have a significant effect on the reliability of the electrical contact system and the working life. Because of the mechanical properties of the contact system, it is extremely difficult to take mechanical methods to overcome the phenomenon. However, after using lubricant on the surface of the contact surface, a surface buffer can be formed to effectively inhibit the occurrence of the contact bounce phenomenon. At the same time, this buffer can also greatly reduce the wear and tear caused by repeated jumps of contact points. Contact lubricant, therefore, not only can make the switch to work more simply, reading showed more accurate and contact the various damage suffered by smaller, and improve the work reliability of the electrical contact system. To sum up, no matter any reason caused by the damage on the surface of the contact, will cause the increase of contact surface contact resistance, contact surface lubrication treatment before and after the change of the contact surface contact resistance is very large, it will directly affect the electrical contact system can function properly. Contact lubricant improves the microvibration of the contact's actual use environment Contact lubricant formed on the surface of the oil film in improving contact surface contamination plays a dual role, can prevent pollutants generated into the contact surface and metal oxide film or organic polymer film, and can enter contact with lubricant pollutants form local thick clumps, These clumps will be removed from the effective electrical contact area as the contacts move. By any kind of processing systems of electric contact are likely to cause the contact surface oxidation and the pollution, so before the lubrication was carried out on the contact surface, contact often has generated metal oxide on the surface, therefore, lubrication was carried out on the contact surface before cleaning is necessary. In this remind engineers should pay special attention to: has been popular with slightly acidic or alkaline lubricant to remove oxide process method is very wrong. Although this process can remove contact on the surface of a metal oxide, and in a short period of time can reduce the contact resistance, but often after for a long time, due to the contact on the surface of the metal itself will continue to suffer from slow erosion and produce a high resistivity of other metal salts, so caused by the high contact resistance of electrical contact system caused by the consequences of premature failure. So of the contact surface has formed metal oxide can choose to have very strong decontamination ability and the performance of rapid evaporation neutral dry contact heating cleaning detergent, and then use to contact lubricating oil or grease lubricant protection treatment. This can effectively reduce contact resistance and improve the reliability of electrical contact system. Contact lubricants improve the silica pollution There has been a great deal of detailed discussion about the contamination of contact points in silicon-contact systems, which are not repeated here. Silicone is widely used for the use of double moisture-proof properties, such as the molds used in the production of plastic products. It is difficult to remove silicon-copper pollution from solvent washing, so it is necessary to strictly control the contamination of silicone. A modified fluorinated lubricant is recommended to repair contact surfaces contaminated by silicone. The lubricants can interact with silicone carbide to form volatile silicosterone fluoride gases. It should be noted: with the constant progress and development of plastic industry and electronic industry, plastic pressure production is widely used in the production of electronic components. For application in electric contact system of plastic pressure, when pressure plastic production must use the release agent in here particularly recommend the use of contact lubricant instead of containing silicone release agent, can achieve very good effect. This method is beneficial to both the production of plastic and the electrical properties of the electrical contact system. How to choose the right touch lubricant The best lubricants are the most suitable contact lubes. There are two main types of contact lubricants that have been commercialized. The other is lubricants based on synthetic lipids. A large number of experimental studies have shown that mineral oil lubricants are easy to carbonize when they encounter arc light discharge, and they are often sticky because they are easily oxidized. But in conductivity, mineral lubricants perform better. Synthetic lubricant can reduce the harm of carbide and sticky on the one hand, on the other hand, it possesses good electrical conductivity, and can greatly improve the performance of work on the contact. Further experimental research shows that mineral oil lubricants can be easily volatilize and contaminated in high temperature environment. To sum up, when choosing contact kinds of lubricant, must according to the actual electric contact system work environment and the corresponding technical indicators and combined with the lubricant itself characteristics, to determine is a mineral or synthetic lubricant. In addition, the following principles should be followed when choosing a contact lubricant: The consistency of the contact lubricant: the choice of the consistency of the lubricant should be determined based on the form and state of the contact in the contact system. Such as the contact for the work of vertical, should choose bigger consistency grease lubricant, if choose oil lubrication is easy to contact surface of the lubricants "run away". Usually, the viscosity of the lubricant must remain unchanged once it is selected. Touch the flash of lubricants for a higher order to prevent fire. 3. Contact lubricant must be compatible with metal material and plastic material on the contact surface. The PH of the contact lubricant should not be acidic or alkaline in order to avoid corrosion of the contact surface metal. 5. Contact lubricants must be able to - 60 - + 160 ? ambient temperature to work in a reliable way. The resistances of the contact lubricant must be kept within a certain range. In principle, the maximum value of the resistance value should protect the current from the closed contact. Minimum value should be able to avoid the leakage of oil bridge when the contact is broken. Contact lubricants should be as non-toxic as possible, while there is no free molecular amount of silicone in the lubricant. How to use the touch lubricant: For customers who have never been touched before, they must be told how to use the product properly when recommending products. And how to make contact lubricants fully play a role in improving the reliability of the electrical contact system, and the key also depends on the method of using the contact lubricant. Regardless of the type of contact lubricants, the following principles must be strictly observed when researching how to use them correctly: To ensure the desired effect, the position of the lubricant should be accurate. 2, to give full play to the contact lubricants finish load transfer in electric contact system when the bridge role, must use accurate measurement of lubricant applied to ensure the precision of lubricant seems, otherwise, will not be able to play the role of lubricant should be. In general, it is recommended to use 0.25 mg of lubricant per 1cm2. Whether or not a contact lubricant needs to be touched before casting is required. In principle, when the contact oxidation has been more serious contamination on the surface, can use first contact cleaner and after fully, then applying contact lubricant, so I can obtain better effect than the contact the lubricant. In order to achieve the consistency of the use effect, the research and application of the tool of lubricants must be taken seriously, regardless of the size of the production target. This is especially important in the areas of mass production.