A composite material is a combination of two materials with different physical and chemical properties. When they are combined they create a material which is specialised to do a certain job, for instance to become stronger, lighter or resistant to electricity.
They can also improve strength and stiffness. The reason for their use over traditional materials is because they improve the properties of their base materials and are applicable in many situations.
What are the Different Types of Composite material?
The range of composites employed in manufacture/construction is extensive, but they fall into these broad categories. These are listed below:
#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.
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.
What are the Advantages of Composite Materials?
- Design Flexibility – Thermoset Composites give designers nearly unlimited flexibility in designing shapes and forms. They be molded into the most intricate components and can be made a wide range of densities and chemical formulations to have precise performance properties.
- Low cost per cubic inch – When comparing costs based on volume, thermoset composites have lower material costs than traditional materials such as wood, engineered thermoplastics and metals. In addition, because thermoset composites have a low petroleum-based content, they are not subjected to the price fluctuations experienced in petroleum-based products.
- Lower material costs – Because thermoset composites can be precisely molded, there is little waste and therefore significantly lower overall material costs than metals products.
- Improved productivity – Industrial Designers and Engineers are able to reduce assembly costs by combining several previously assembles parts into a single component. Also, inserts can be molded directly into the part during the molding process thereby eliminating the need for a post-process. In addition, composites do not usually require additional machining, thereby reducing work-in-process and time to market.
Why use Composite materials?
The most obvious characteristic of composites is that they are lightweight and durable. The general purpose of making composites is to reduce the weight of the manufactured material, increase its durability, heat resistance and conductivity.
Apart from this, the composite material retains its durability and lightness while remaining resistant to wear.
#1. Composites Have A High Strength-To-Weight Ratio.
Perhaps the biggest advantage of composites is their high strength-to-weight ratio. Carbon fiber weighs about 25% as much as steel and 70% as much as aluminum, and is much stronger and stiffer than both materials per weight.
High-end auto engineers use composites to decrease vehicle weight by as much as 60% while improving crash safety; multilayer composite laminates absorb more energy than traditional single-layer steel. Harnessing the power of composites benefits manufacturers and consumers alike.
#2. Composites Are Durable.
Composites never rust, regardless of their environment (though they are prone to corrosion when bonded to metal parts). Composites have less fracture toughness than metals but more than most polymers.
Their high dimensional stability allows them to maintain their shape, whether hot or cold, wet or dry. This makes them a popular material for outdoor structures like wind turbine blades.
Engineers choose composites over traditional materials to reduce maintenance costs and ensure long-term stability, major benefits for structures that are designed to last decades.
#3. Composites Open Up New Design Options.
Composites offer design options that would be hard to achieve with traditional materials. Composites allow for part consolidation; a single composite part can replace a full assembly of metal parts.
The surface texture can be altered to mimic any finish, from smooth to textured. Over 90% of recreational boat hulls are constructed from composites, in part because fiberglass can be molded into a wide range of boat shapes. These benefits save production time and reduce maintenance costs in the long run.
#4. Composites Are Now Easier To Produce.
In the past, engineers had to use a complex lay-up process to fabricate composites, which was time-consuming and restricted the design geometry. Digital Composite Manufacturing (DCM) has changed this.
DCM is a patented manufacturing process that fabricates composite parts without manual labor. With DCM, composites can be tailored in three dimensions locally or globally, creating just the right strength, density, and flexibility for the project.
DCM is enabling engineers to design for the flexibility of 3D printing, combined with the high performance of composites.
How Are Composite Materials Manufactured?
There are a few different ways to manufacture a composite material. The type of manufacturing used will be dependent on the makeup of the composite material itself as well as the intended use of the product. Below we outline some of the common ways we manufacture composite materials at Spartec Composites.
#1. Resin Infusion
resin infusion, specifically Vacuum Assisted Resin Transfer Molding, is one of our specialties at Spartec Composites.
In this method, composite materials are infused through a vacuum pulling in the resin, like water through a straw. This style of composite manufacturing is used in a variety of applications including aerospace components, boat hulls and vehicle body panels.
#2. Hand Lay-up
had lay-up involves manufacturing composite materials by hand. This type of composite manufacturing allows the manufacturing of high-quality crafted products and has been used to manufacture art sculptures, horse racing helmets, hockey helmets and retail store fixtures to name a few.
#3. Pre-Preg
pre-reg composite manifesting involves fabrics being pre-impregnated with specialized resins and frozen in a pre-cured state. This allows for detailed cutting and placement before completing the process in an oven.
#4. Autoclave Curing
autoclave curing is an important component of the composite manufacturing process. In order to produce the highest quality laminates. At Spartec Composites, our equipment allows for up to 20 times atmospheric pressure during the cure cycle to squeeze fibre bundles tightly and optimize the process.
#5. 3D Printing
some composite manufacturing processes can utilize the precision of 3D printing to create intricate products that would be challenging to craft by hand.
#6. Urethane Casting
Urethane casting allows for the manufacturing of composites that include plastic and rubber parts. It is ideal for projects that are not large enough for or where pre-preg composite manufacturing would not be cost-effective.
Examples of Composite Uses
- Electrical equipment
- Aerospace structures
- Infrastructure
- Pipes and tanks
- Homes can be framed using plastic laminated beams