What are the two types of composite materials?

Link to KLS

Composite materials are formed by two or more components so that the properties of the final material are better than the properties of the components separately.

This kind of materials consist of:

• Matrix: sets up the part geometrically, gives cohesion to the material, it is usually flexible and not very resistant and transmits efforts from one fibre to another.
• Reinforcement: provides rigidity and resistance.

Composite materials examples

• Plastics reinforced with glass fibre or other fibres.
• Metal matrix composite materials.
• Ceramic matrix composite materials
• Ceramic-metal composites.
• Concrete.
• Wood composites: Oriented strand board (OSB),  engineered wood, such as plywood, etc.

Types of matrices and reinforcements in composites

Depending on the type of matrix there are:

• Metal matrix composite materials
• Ceramic matrix composite materials
• Organic, polymeric or Reinforced-Plastics matrix composite materials. This group includes:
  • Composite materials of long fibre reinforcement with a plastic matrix.
  • Fiberglass composite materials with a plastic matrix.

Regarding reinforcements, there are different types of them, such as carbon fibres, glass fibres, aramid fibres, natural fibres, etc.

Long fibre-reinforced composite materials

The most used ones because of their lightness and excellent mechanical properties, are composite materials of polymeric matrix with fibre reinforcements. These materials replace others (mainly metallic ones) in those applications in which the mechanical properties-weight relation influences decisively the maintenance costs of the product.

Organic matrices can be thermoplastic, thermosetting or elastomers.

Thermosetting matrices or resins are the most used in high-performance composite materials. These resins result in a solid, insoluble and unmeltable product by a series of chemical reactions known as curing or cross-linking. In contrast, the thermoplastic ones melt when exposed to heat.

The main fibres used as reinforcements are:

• Glass fibres
• Carbon fibres
• Boron fibres
• Ceramic fibres
• Metal fibres
• Aramid fibres
• Natural fibres: sisal, hemp, flax, etc.

Regardless of the type of material they are made of, fibres can appear in form of roving, mats, or fabrics.

Another type of products that are incorporated into the composite material fibre-resin is fillers and additives. They are added with the aim of providing particular characteristics to the material or reducing its cost.

The number of added products varies depending on the properties we want to achieve. The general aim is to improve processability and the finished product.

Structural composite materials

Structural composite materials can be classified as follows:

• Sandwich structures:  composed by a core and layers. They allow to improve the mechanical properties but without an excessive increase of weight. They also improve thermal and acoustic insulation.
• Monolithic structures: parts with a complex geometry, formed by overlapping fabrics with particular orientations that allow obtaining specific characteristics. This kind of parts is intended to withstand the heaviest structural loads.

AIMPLAS has a broad experience in long-fibre composites materials working in different projects to obtain high-added value composites products or to improve the production process.

Types of Composite Materials

1. Nanocomposites

Nanocomposites are both man-made and naturally occurring. The reinforcer is generally a nanomaterial such as carbon nanotubes or graphene added to a polymer matrix, or silicon nanoparticles added to steel to induce fine crystal growth. In some applications, calcium carbonate or talc can also be effective in making polymers stiffer and stronger.

Typical nanocomposites use the nanomaterial additive to add strength, stiffness, and other properties such as electrical or thermal conductivity to the polymer matrix. Naturally occurring nanocomposite examples are bone and shell. Nanomaterials represent significant health risks in some cases, so manufacture of these materials can be challenging.

2. Metal Matrix Composites (MMCs)

MMCs use a metal matrix like aluminum or magnesium and a high-strength fiber reinforcer in particle or whisker form. Reinforcers are generally carbon fiber or silicon carbide particles. This develops unique properties that go beyond the basic metal component's limits, including increased strength and stiffness, elevated temperature resistance before the onset of weakening, improved wear resistance, and reduced coefficient of thermal expansion. 

If you want to learn more, please visit our website copper composite material.

MMCs are used in aerospace industries and extreme automotive uses, delivering high strength and low weight. They are also used in electronics, medical devices, and sporting goods. The processing of MMCs is more challenging than most other classes of composites, as high temperatures and the difficulties of uniform reinforcer distribution are challenging.

3. Polymer Matrix Composites (PMCs)

PMCs are the most prevalent and easily understood forms of composite materials. This term encompasses the hand lay-up of carbon fiber and glass fiber fabrics and the manual, injected, or pre-impregnated epoxies and polyester resins that form the matrix. These materials offer various benefits including high stiffness and strength (compared with the part weight), great thermal, chemical, and mechanical resilience, and abrasion resistance. On the other hand, PMC requires highly skilled labor, resulting in higher costs, though these are often not excessive for applications that need a high-strength outcome.

PMCs are widely used in aerospace, automotive, marine, and sporting goods, benefitting from light weight, high strength, and stiffness. Production of PMCs involves assembly methods such as hand lay-up and filament winding, which can be slow. Precise control over the curing process is needed, to achieve ideal material properties.

4. Glass Fiber Reinforced Polymers (GFRPs)

GFRPs are a subset of polymer matrix composites, specific to epoxy and polyester bonded glass fiber materials. The glass fiber can be in chopped strands, lending a degree of anisotropic strength to structures by the mixed orientation of the fibers. The reinforcer can also comprise chopped strand roving (or fabric), making a more orderly process but less well suited to bulk components as fibers are all laid in one plane. Woven roving improves the quality of lay-up and can offer greater strength, at a price.

5. Hybrid Composites

Hybrid composites are those in which two or more different reinforcing fibers are integrated into the final material. This could be a combination of glass and carbon fiber in a lay-up'for enhanced impact resistance or cosmetic reasons. It is common to use titanium mesh or strands in the manufacture of racquets for ball sports, to improve tensile and bending performance. These materials can be challenging, as compatibility issues can affect the behavior of the material'for example, one fiber may bond better to the matrix than the other. Considerable testing is required to confirm the value or feasibility of the hybrid matrix. They have the same applications as PMCs, but the higher cost restricts their use.

6. Ceramic Matrix Composites (CMCs)

CMCs consist of a ceramic matrix and reinforcing fibers. A ceramic matrix provides extreme temperature and corrosion resistance and excellent wear properties. But ceramics are generally brittle when unreinforced. The addition of silicon carbide, alumina, or carbon fibers can counter the brittleness to make a more serviceable material.

CMCs are used to make gas turbine blades, specialist rocket/aerospace components, and heat exchangers. CMCs are very costly and they remain quite brittle, which limits their use. However, this is a field of intense research, and properties are improving.

7. Natural Fiber Composites (NFCs)

There is an increasing trend toward using natural fibers in composite manufacture, to reduce the environmental impact of materials use. Natural fibers such as jute, flax, cotton, and wood are used in a variety of ways. Automotive interior panels are commonly made from resin-bonded natural fibers which are compression molded to shape and then upholstered in plastics or leather for final surfacing. Wood fibers are added to polymers for FDM/FFF rapid prototyping filaments, to improve strength and produce a wood effect. Skateboard decks make extensive use of natural fiber reinforcement, generally in a polyester resin matrix.

8. Carbon Fiber Reinforced Polymers (CFRPs)

CFRPs are another subset of polymer matrix composites, specific to epoxy and polyester-bonded carbon fibers. For hand lay-up purposes, carbon fiber is generally used as woven roving, with a range of weave patterns used for various types of loading and stress distribution. The fibers are pre-impregnated with thermally activated resins, so the flexible cloth is laid-up and then compressed and baked to liquify and then cure the resin to create a rigid, tough result. Carbon fiber can also be pultruded with a range of polymers, to make continuous lengths of CFRP in complex sections. 

9. Aramid Fiber Reinforced Polymers (AFRPs)

AFRPs are another subset of polymer matrix composites that employ aramid as the reinforcer. Aramid fiber composites are used in the highest-impact applications. The aramid is generally used as woven fabrics that are pre-impregnated with appropriate epoxy and polyester resins, to be processed as per carbon/glass fiber. Another aramid reinforced composite is the paper/aramid honeycomb material used in low-profile flooring panels in aviation'layered with aluminum sheets and epoxy bonded, this is a typical high-value hybrid composite.

10. Functionally Graded Composites (FGCs)

FGCs are essentially a subset of any type of composite. These are composite materials in which the constituent parts can be modified in the application or type through the structure to tune performance. A gradual transition in properties is used to avoid stress concentrations at sudden changes. The functional grading can be as simple as adding or altering fiber content at elevated stress points; changes in weave pattern in roving to alter load distribution; or progressive hybridization for impact resilience in regions.

FGCs are used to make lighter and more resilient aircraft and spacecraft components, such as turbine blades and rocket nozzles. Biomedical devices/implants can have varied properties regionalized according to desired tissue interactions. 

Advantages and Disadvantages of Using Composite Materials in 3D Printing

Fiber and metal additives in 3D printing materials offer some potential advantages. These are listed below:

1. Deliver increased strength and stiffness, allowing more functional printed outcomes or reduced weight for the same strength.
2. Can be more durable than matrix material alone. This may enable parts to function at higher temperatures.
3. Some composite additives can add electrical or thermal conductivity or increase breakdown voltage.

Some 3D printing processes use a form of functional grading, by co-printing rigid and elastomeric materials in the same parts, allowing properties to be varied through a build. 

There are also challenges in using composites in some 3D printing processes, as listed below:

1. Additive-loaded materials can bring processing challenges. For example, they can be difficult to shape using established technologies. 
2. Few options are on the market as yet, so availability can be a challenge.
3. Highly functional composite print materials are more costly than their basic alternatives.

Industrial Applications of Composite Materials

Listed below are some industrial applications of composite materials:

1. Motorcycle fairings, kayaks, boat hulls, and aircraft skins.
2. Epoxy-bonded carbon fiber in fishing rods.
3. Plywood for construction.
4. Ferroconcrete for construction.
5. Glass-reinforced plastic for high-strength molding.
6. Aircraft flooring, sandwiching paper honeycomb between two aluminum sheets.
7. Spectacle frames (often mold plastic over a metal structure).

Xometry provides a wide range of manufacturing capabilities, including 3D printing, CNC machining, and injection molding for prototyping and production parts. We work with composite materials on many projects. Get your instant quote to get your project started.

Copyright and Trademark Notices

1. Kevlar® is a trademark of E. I. DuPont de Nemours and Company

Disclaimer

The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry's network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.

The company is the world’s best copper clad stainless steel sheets supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.