(Source: Textreme )
As we covered in pt1 (https://steemit.com/science/@kanu1988/carbon-fiber-pt1 ) how carbon fibers are made, in this part we will cover how to „convert“ carbon fiber in something more useful or in other words how to make composite material.
First of all composite materials are materials composed on minimal two parts with different properties, those parts are matrices and reinforcement. Matrices are parts of composite that connect reinforcements and hold it in one piece, polimers are usually used as matrices like eopxy, poliester, vinil, fenol resins. As reinforcements are used carbon fiber, fiberglass, aramid fibers, natural fibers( hemp, silk etc. ), tegris, basalt and hybrids.
Usually when people say composite materials they think of carbon fiber but it all started much earlier, so one of the first composite was used in building houses it was from mud and grass usually molded in bricks, mud was used as matrices and grass as reinforcement. In newer days you could see composites everywhere like concert (water as matrices, sand and stones as reinforcement) or asphalt.
To get composite you have to connect somehow those parts there are few techniques we will cower in this parts regarding to carbon fiber reinforced composites.
1.First to start with hand layup, the carbon fiber cloth is placed on the mold surface or surface we wont to cover after that resin is applied usually with brush, after the desired layer number composite is leaved to cure( it have to past some time to get resin fully connected and hardened ), it can be helped with rising temperatures ( but again not to hot ). After some time ( usually 6-24h ) we can demold the composite and thats it, eventually trim the edges or cut hole if they are needed.
(Source: honda50.tboltusa )
2.Vacuum bagging- process is similar to previous but after wetting the fibers whole thing is put under the vacuum and squeeze all unwanted resin and put pressure on fabric for better mold surface transfer. For this process are needed some more parts like vacuum pump, seal bag, sealant tape, hose connector, catch port, peel ply, some kind of mold release.
(Source: jamestowndistributors )
3.Resin infusion. similar on equipment like vacuum bagging, in this case we put reinforcement and matrices in different order, first we put reinforcement on to the mold which was covered with release then peel-ply or release film, flow mesh and vacuum bag, but there are two hose connector one for vacuum and one for resin. After all thing are in the mold we pull out the air with vacuum pump in this step we have to ensure that every part of bag is sealed and there is no way that air can came in, the bag in this stat is usually leaved for some time( 1-12h) to see if there are any leaks, in catch port there is usually pressure gauge so if there are any leaks it will be visible on pressure change. Then if everything is ok, valve on the hose with resin is opened and resin flows through fibers and wetting them, this is one of best way to get great fiber to resin ration and perfect surface finish if the mold is in good shape. Also its recommended to put part in over or autoclave to rise temperature for better curing process.
(Source: composite-integration )
4.Resin transfer molding similar to previous but the resin is usually departed with pump pressure and vacuum bag is replaced with upper mold so fiber are being wetted with pressurizes resin, something like injection molding of plastic.
(Source: .moldedfiberglass)
- Prepreg short for preimpregnated fabric, as the name says, when you buy it fiber and resin are combined already, because of this its usually stored on low temperatures not to start chemical process in resin.
This type of materiall is used highly beacouse it is easy for use, dont create big mess, its easy to cutt with cnc or scizors, its easy tu put different orientation leyes, but you will need a better equipment like autoclave and vacuum pump.
(Source: avtcomposites) - Filament winding is process crating usually cylindrical shape objects because axis on which the filament is winded rotates , you could make square or something like objects, its commonly used for rocket bodies, tubes, gas canisters etc, this will be covered in specific blog .
(Source: bikerumor)
This is the end of part 2, stay true for the nex one.