The demand for adhesives and sealing materials does not weaken even with the advent of increasingly advanced composites and spot welding technology. Obviously, traditional means of sealing assembly joints like flax and FUM tape have long ceased to compete with adhesive sealing means. The most technologically advanced representative of this area is anaerobic adhesive, which is used by both professionals and home craftsmen.
Material Overview
The tool is a special type of adhesive materials that act as seals and sealants. Such compounds are called anaerobic due to the lack of an oxygen medium in the zone of action. At the time of applying such glue to the target surface, a rapid flow of air occurs with the creation of an oxygen-free atmosphere, as a result of which favorable conditions are formed for curing the material. In physical and chemical terms, anaerobic adhesive can be represented as a polymer liquid mixture, which is supplied in the form of a paste, gel or even aerosol.
Material Applications
This type of composition is used in a variety of industries - from household to aerospace. By the way, in Russia, the distribution of anaerobic products is associated with the active development of rocket and space equipment in the middle of the last century. At first they were used to lock the threaded elements in order to prevent arbitrary loosening of the nuts. It is in this quality that this material is used today. Moreover, anaerobic thread sealant adhesive on the market forms the basis for pipe seals. It is also used to eliminate minor defects on the surface of sheet metal, to strengthen welds and fix various joints. Directly in the form of glue, this tool is recommended to be applied to flat surfaces. In industry, the material helps to modify the characteristics and structural qualities of powder metallurgy products.
Glue composition
Most anaerobic materials are based on the following components:
- Acrylic oligomers and monomers.
- Substances initiating adhesive activity.
- Inhibitors (stabilizing group).
- Functional inclusion. The use of the components of this spectrum is individual and depends on the formulation of a particular manufacturer. In particular, colorants, plasticizers, thickeners, frost-resistant additives, etc. can be used.
Inhibitors and activators of anaerobic glue, which determine the functional qualities of the composition, deserve special attention. By initiators is meant hydroperoxide, which causes the processes of free radical polymerization. In combination with reaction accelerators (amines and heterocyclic nitrogen-containing compounds), it provides a decrease in the polymerization temperature. As for the activators, their main task is to accelerate the cure. Copper salts, organic solutions, and sulfur-containing nitrogen compounds represent this category of components.
Operating principle
The acrylic group has the main sealing and adhesive effect, forming spatially cross-linked polymer structures. The interaction of the substances of the initiating group with the metal structure promotes the formation of radicals, due to which oxygen is consumed. Against this background, the curing process intensifies. It is important to emphasize that metal as such is a necessary participant in the polymerization process, due to which the anaerobic composition of the thread sealant from the liquid state passes into the structure of the solid polymer. Another thing is that different metals, due to the peculiarities of their own molecular structure, can interact differently with the same activators. For example, iron, copper and steel contribute to the acceleration of polymerization (solidification), since they are involved in redox reactions. As a result, preforms of these metals are sealed 2-3 hours after application of the composition. In the case of aluminum, chromium and alloyed steel alloys, the curing process to the required state can take 5-7 hours. But the manufacturers themselves, regardless of the target material, recommend that the machined part be introduced into the operational process only after 24 hours.
Operational properties
Anaerobic sealing materials are characterized by the following qualities:
- The combination of viscosity and fluidity is within the limits allowed for work with gaps with a thickness of 0.07 to 0.5 mm.
- Durability - preservation of basic characteristics for at least 12 months.
- High intensity cure at room temperature.
- One-component - the composition is sold in finished form, so it does not need to be diluted with special additives.
- Strength properties - best manifested in the adhesive-fixer, which is suitable for the repair of metal, enamel, ceramic and graphite materials.
- Corrosion resistance - especially beneficial for metal products, the threaded sections of which do not have their own rust protection.
- Resistance to oil substances, due to which the composition can be applied to new surfaces of new pipes with factory lubrication.
Glue varieties
Despite the general technological basis and similar component filling, anaerobic formulations receive different sets of technical and physical properties due to modifiers, which leads to their division into the following types:
- Sleeve clamps. Designed to service mechanical parts of various equipment - for example, bearings, gears, bushings, spindles, cylinders, etc. Such compositions demonstrate high bearing capacity for cylindrical fasteners, reducing stress during operation of the elements.
- Plumbing sealants replacing traditional polytetrafluoroethylene pastes and tapes. Used as pipe and threaded seals. Among the operational features, one can distinguish the rapid polymerization effect, the absence of vaporization and melting at high temperatures, as well as in some formulations providing the lubrication effect.
- Locking adhesive mixtures. They are used in industry - in particular, in automobiles and mechanical engineering during assembly processes and in maintenance. During operation, fill gaps in threaded joints, reducing vibration effects.
Application Technology
Before use, the product must be shaken in the package, clean the work surface and prepare a clean rag or napkin to remove excess glue. The composition is applied to the working area with a thick layer so that the entire joint area is covered. In the case of a threaded fastener for pipes, the sealant is laid both outside and inside the workpieces along a helical ditch. Next, the composition is evenly distributed, and then the connection is made. The surplus that has come out must be immediately eliminated by carefully cleaning the contaminated surfaces.
Optimum Health Conditions
To make the most of the properties of the anaerobic material, it is advisable to think through the favorable conditions for its operation in advance. So, the temperature is a serious factor - these agents work best at 18-30 ° . It is desirable to prevent contact of the treated surface with aggressive media such as acids, solvents and alkalis, which will corrode the structure of the polymer fabric. Many compositions of anaerobic adhesives are sensitive to mechanical stress, and this also applies to small vibrations. Therefore, it is recommended to securely fix pipes and other structures, preventing even the slightest vibration.
Conclusion
From the point of view of efficiency, the anaerobic sealing principle for various kinds of threaded fasteners is optimal. It has practically no negative operational factors, if you do not take into account the complexity of dismantling. It is necessary to disassemble the structures treated with anaerobic adhesive-sealant with the connection of a building hair dryer, the hot flows of which will destroy the polymer structure. Also, in choosing this method of compaction of compounds, one should keep in mind the financial aspect. So, on average, manufacturers ask for 400-500 rubles for 50 ml of anaerobic composition. For comparison, traditional means of sealing and sealing will cost several times cheaper, which is especially noticeable with regular maintenance of threaded joints in large volumes.