Conductive paste is used to reduce resistance at the junction of electrical contacts.
What is pasta for?
Back in the second half of the 20th century, scientists calculated that energy losses in all areas of production account for up to 10% of total electricity consumption. This value increases with aging equipment and wiring wear.
The easiest way to minimize losses without serious financial costs was the use of special electrically conductive means. In this case, there is no need to repair equipment and carry out wiring replacement.
Electrical contacts have their own service life. And it shrinks when the transition contact resistance changes. When exposed to electricity, the junction of the wires begins to warm up. This can even lead to fires. Statistics say that in 10% of cases of industrial accidents occur precisely because of the destruction of the contacts of the electrical network. And the destruction of this kind occurs precisely because of exceeding the limit of electrical resistance.
For the processing of contacts, standards include substances such as lithol, ciatim, petroleum jelly. All of them have a fatty base. Due to this, such funds are smelted and burned out, leaving the contact unprotected. In recent years, as a replacement for them, contact-conductive paste has been increasingly used.
General concept
The conductive paste allows you to increase the service life of the contacts of the electrical wiring up to seven years. It halves the value of the transition resistance in places of electrical contacts. This tool works in temperature conditions up to 350-4000 degrees. In such conditions, it allows you to save all the functional features of contact compounds.
Separately, there is such a type of agent as anti-corrosive conductive paste. In addition to the main tasks of reducing the transient resistance, it protects the contacts from moisture and aggressive environment.
Electrically conductive lubricants also perform an energy-saving function. Experts estimate that using only 1 kg of the product can save up to 100 thousand kW of electricity per year.
Application area
Conductive paste for contacts is used in various fields of production and industry. The main ones are:
- Power plants of various types (thermal, nuclear, hydro).
- Repair of electrical circuits.
Classification
Electrically conductive paste has two types. They differ among themselves in the way they affect the contacts:
- Passive (it is also called neutral) is a kind of prophylactic that will protect against oxidation of contacts under the influence of atmospheric oxygen. This group includes KVT contact conductive paste.
- Active does not affect the metal wires, but have an effect on oxidized areas located not on the surface.
Use of funds
Conductive paste is easy to use. First of all, the surface on which the product will be applied must be degreased and dried.
Next, the paste itself is prepared. As a rule, it consists of two components: a powder with the addition of metal, a liquid to dilute the powder. Therefore, the components must be connected. This is done in a dry container. It is possible even on cardboard, if the quantity is small. The consistency of the paste should resemble a toothpaste.
The paste is applied to the prepared surface in advance with a layer of 2-3 mm thickness. When connecting the contacts, their ends are simply lowered into the tool.
It is necessary to work with ready-made pasta quickly. She grasps in two minutes. Drying time is two hours.
DIY pasta making
Conductive paste is commercially available in a wide range from various manufacturers. But it can also be made independently.
The main component of the glue is synthetic resin. It does not conduct electricity in its pure form. Therefore, metal particles are added to it - gold, copper, silver, nickel. To ensure good electrical conductivity, the volume of powder should be at least 70%.
The most commonly used silver. Such a choice is based only on the economic side of the issue. The simplest and cheapest way to obtain it is through a chemical reaction of formalin reduction. For this, one part of silver nitrate and one part of formalin (1%) are taken. Their mixture is heated to a temperature of 80 degrees. After that, ammonia (5%) is added there. As a result of the reaction, a dark silver precipitate will fall to the bottom. This precipitate is filtered, washed and dried.
When all the ingredients are ready, you can cook the paste. To do this, combine 100 grams of epoxy resin, 250 grams of silver powder, 10 grams of dibutylflatate (to give the resin a more liquid consistency). Before use, add 10 grams of polyethylene polyamine as a hardener. Without it, the mixture can be stored for unlimited time.
It is possible to increase the electrical conductivity of the paste if it is dried after application at elevated temperatures (up to 100 degrees).
Electrically conductive agents are chemicals that must be handled in compliance with basic safety rules. The paste should not get on the skin and mucous membranes. If this happens, rinse thoroughly with warm water and soap.