What’s Composite Material? Types and Uses

Composite materials combine two different materials having varying chemical and physical properties. This combination leads to the creation of a material designed to perform a specific task such as becoming electricity-resistant, lighter, stronger, or improving stiffness. 

One reason users prefer composite materials in contrast to traditional materials is due to their ability to improve their base material’s properties. Another reason is their usefulness in different applications.

Brief History

The human use of composites can be dated back to a thousand years ago. The creation of the first composites was in 3400 B.C. in Iraq. This ancient society joined wood strips on each other at varying angles to create plywood. Then around 2181 B.C, the Egyptians began to produce death masks from linen or plaster-soaked papyrus. After that, both societies began reinforcing their materials using straw to help strengthen boats, pottery, and bricks.

1200 A.D, the Mongols started engineering composite bows that were very effective back then. They were manufactured from bone, wood, silk, horn, cattle tendons, and bamboo that has been bonded using pine resin.

After the industrial revolution, synthetic resins took solid forms through polymerization. During the 1900s, this knowledge regarding chemicals resulted in the creation of different plastics like vinyl, phenolic, and polyester. The development of synthetics soon began and Leo Baekeland, a chemist created Bakelite. Due to its heat-resistant nature and inability to conduct electricity, it is useful in different industries.

In the 1930s came a very great time for the development of compound material, named “composites”. Owens Corning developed glass fiber and was involved in the creation of the fiber-reinforced polymer industry. These engineered resins are still useful today and the patenting of unsaturated polyester resins took place in 1936. Two years later, resin systems with higher performance became accessible.

In 1961, the carbon fiber (first-ever) was patented; it was then commercially available. During the mid-1990s, composites became very common for construction and manufacturing processes as a result of their low cost in contrast to the material previously used.

A Boeing 787 Dreamliner’s composites during the mid-2000s proved their utilization in high-strength applications.

What’s a Composite Material?

Composite is a compound material made by combining two or more constituents, each having different chemical and physical characteristics. This type of combination usually produces a material designed to perform a certain function. For example, they could be lighter, stronger, or more resistant to electricity. Consequently, a composite material can also improve strength, stiffness, and durability

They are more preferred to traditional materials since they are known to enhance the features of their base materials and are useful in most of the industrial applications, automotive, aerospace, marine, energy, etc.

Despite the dissimilar physical or chemical properties of each constituent material, they are combined to produce a material with unique properties, different from their individual elements. Within the combined structure, these individual elements are separate, hence, distinguishing composites from solid solutions and mixtures.

Examples of engineered composites include:

• composite wood like plywood
• metal matrix composites
• Reinforced concrete and masonry
• ceramic matrix composites 
• Reinforced plastics like fiberglass or fiber-reinforced polymer. 

There are various reasons why new materials can be included in this category. These materials are stronger, less expensive, lighter, or more durable than common materials.

Researchers have started including advanced features like computation, sensing, communication, and actuation into composites, commonly known as robotic materials.

Composite materials are known for their wide range of applications, especially in buildings and bridges. They are also generally used for structures like swimming pool panels, storage tanks, countertops, shower stalls, racing car bodies, imitation granite, cultured marble sinks, and boat hulls. Also, they are becoming more popular in automotive applications. Other advanced examples are great for use in demanding environments like aircraft and spacecraft.

What are Composites made of?

Composites are manufactured from a specific polymer matrix, which has been reinforced with a natural, artificial fiber such as aramid, glass carbon, as well as other reinforcing materials.

The matrix offers protection to the fibers from any external or environmental damage and helps in transferring the load between these fibers. Furthermore, the fibers offer stiffness and tensile strength for reinforcing the matrix and also aid in resisting fractures and cracks.

In most industry products, the matrix is polyester resin while the reinforcement is glass fiber. However, there are many blends of reinforcement materials and resins utilized in composites. However, many combinations of reinforcements and resins are utilized in composites with each material contributing to the special properties of the completed product. Fiber is powerful but brittle, and offers stiffness and tensile strength, while resins that are more flexible offer shape and give the fiber protection.

Synthetic and Natural Composites

Composite materials can come in natural or synthetic form. For instance, wood is a natural composite that consists of wood fiber and lignin. The fibers contribute to the strength of the wood while the lignin binds it and offers stability. 

On the other hand, plywood is a composite that consists of both synthetic and natural materials. In the case of plywood, thin layers of veneer form flat sheets that are stronger compared to natural wood.

Are Plastics Composites? 

While some plastics are composites, some are pure plastics.  For example, aramid fiber-reinforced plastics are popular in manufacturing and closely mimic the properties of Kelvar plastics, which are used for armor plates and helmets. Consequently, other plastics like polyester and epoxy resins are reinforced with secondary material in small amounts. So, they increase the mechanical strength and durability without losing the original properties of base plastic.

How Composites are Made in Factories? 

You might be confused with man-made composites and industrial composites, they are essentially the same things.  All the composites that are not available by nature are referred to as man-made, whether you layup manually or use a machine to make them.

In factories, there are different methods; Resin transfer molding (RTM), spray-up, pultrusion, autoclave processing, filament welding, etc. However, manufacturing companies do not make the composites themselves. They choose the right composite from suppliers and machine them into finished composite parts or products according to designed specifications.

Major Properties of Composite Materials

Composite materials feature some distinct properties which make them useful in the most demanding applications. These properties of composites contribute to their performance.

Let’s discuss various properties that are highly beneficial for manufacturing projects. 

Durability 

The composite of materials can be used in harsh weather conditions or corrosive environments. Also, they perform well under repetitive stress like mechanical shocks and vibrations. All these make them a perfect choice for spacecraft, automotive, and aerospace applications among others.

Impact resistance 

Composites are designed to tolerate and dissipate impact forces without damaging them. This is an important property for applications that are exposed to impacts. Their resistance to damage from collisions or shock makes them essential in crash structures.

Strength 

Composites are known to be stronger than their constituent materials. They enhance strength and sturdiness, making them a great option for applications that need high load-bearing capacity.

Flexibility 

Composites are flexible enough for bending and deformation. They can be designed to bend in different directions without breaking. Their flexible nature contributes to their wide use in the production of prosthetic limbs. Also, the composite of materials offers engineers and designers a better option in applications exposed to dynamic loads or vibration.

Chemical resistance

Composites can survive attacks that come from harsh chemicals or environments. Therefore, they are ideal for chemical-resistant coatings and chemical-processing equipment 

Lightweight

Composites are power-packed materials that enable the production of lightweight components and structures. Their high strength to weight ratio serves as a critical property in industries where weight reduction is a priority.

Thermal stability

The composite material can resist deformation in high thermal conditions. This ability to maintain their structural integrity in such conditions is an important consideration for applications exposed to extreme temperatures. 

Electrical conductivity

Composites have excellent electrical conductivity. These materials are designed to achieve great electrical properties like insulation or conductivity.

Acoustic insulation 

Another distinguishing feature of composites is their ability to reduce or prevent noise transmission. This sound insulation property makes it perfect for soundproofing applications.

What are the Benefits of Composites?

Composites have become a popular material we use every day. From the cars we drive to the golf equipment we use to the pipes used in our environment, these materials have a huge function to play. Even some sophisticated devices like rocket ships need composite to function. The importance of these materials in our environment and daily lives can’t be overemphasized.

Composites, when compared to traditional materials, offer much more benefits. This can be attributed to their unique properties. Therefore, they have become a more popular choice amongst engineers, designers, and architects. In some demanding environments where thermal stability or extreme strength is a priority, composites are usually the go-to material.

Lower costs

Composites are more economical than traditional materials like wood and metal. Aside from being less expensive, they offer a greater function. Also, they are more environmentally-friendly, since they feature less waste.

Less production time and effort

Using composite in production lessens the time and effort used in assembling different traditional materials.

Design flexibility 

Another benefit of composite materials is that engineers can conform them into any desired forms and shapes. Therefore, they can create intricate components from these materials.

Types of Composite Materials

Several composite types are available based on the type of material matrix and reinforcing medium. They offer distinct physical and mechanical properties, making them suitable for a wide range of requirements. 

The following are some common types; 

Nanocomposites

This type of composite material exists either in a natural or artificial form. Generally, the reinforcer exists as a nanomaterial like grapheme or carbon nanotubes which are added to the polymer mix. It could also be the addition of silicon nanoparticles to steel to ensure a fine and perfect crystal growth. 

Talc or calcium carbonate could be effective in ensuring stronger and stiffer polymer composites in some applications.

Typical Nanocomposites utilize nanomaterial additives to add stiffness, strength, as well as other properties including thermal or electrical conductivity to different polymer matrices. Their natural examples include shell and bone. Furthermore, in some situations, nanomaterials represent huge health risks, therefore manufacturing these materials could be an issue.

Metal Matrix Composites (MMCs)

Metal matrix composites utilize a metal matrix such as magnesium or aluminum as well as a fiber reinforcer of high strength in whisker or particle form. 

Generally, reinforcers are silicon carbide or carbon fiber particles, which creates special properties that surpasses the limits of basic metal components, which includes increase in temperature resistance, increase in strength, before the start of better wear resistance, weakening, and reduced thermal expansion coefficient.

Furthermore, metal matrix composites are useful in the automotive and aerospace industries and offer low weight and high strength. Also, they are useful in sporting goods, medical devices, and electronics. The processing of these composites is more difficult in contrast to most types of composites. This is because of high temperatures, as well as the issues with the uniform distribution of the reinforcer.

Polymer Matrix Composites (PMCs)

These are the most easily understood and prevalent forms of composite material. The term includes the hand lay-up of glass fiber and carbon fiber fabrics as well as the injected, manual, or pre-impregnated polyester and epoxies resins that form the matrix.

In addition, PMC composite materials provide different benefits, which include high strength and stiffness (in contrast to part weight), and high chemical, thermal, abrasion, and mechanical resistance. Furthermore, polymer matrix composites require very skilled labor, which means higher costs, although they are usually not excessive for any application requiring high-strength outcomes.

Also, PMCs are very useful in marine, automotive, aerospace, as well as sporting goods, enjoying the benefits of stiffness, high strength, and lightweight. Manufacturing PMCs deal with assembly methods like filament winding and hand lay-up, which could be a slow process. There is a need to have accurate control over the entire curing process to achieve the most appropriate material properties.

Glass Fiber Reinforced Polymers (GFRPs)

These form a group of the polymer matrix composites that are specific to polyester and epoxy bonded glass fiber materials. These glass fibers could be inside chopped strands, offering some anisotropic strength to the structures through the mixed orientation of these fibers. 

Also, the reinforcer could involve fabric, which will make the process more orderly but not suitable for bulk components because all the fibers are laid in a plane. With woven roving, you can improve the lay-up’s quality, and achieve greater strength.

Hybrid Composites

These composites exist as at least two different reinforcing fibers, which are incorporated into the eventual material. The combination could be that of carbon fiber and glass in a lay-up – to ensure better resistance. When manufacturing racquets, it is a common practice to utilize titanium strands or mesh. This helps in improving the bending and tensile performance.

The materials could be challenging because compatibility issues could affect a material’s behavior – for example, a specific fiber might form a better bond in contrast to the other. There is a need for considerable testing to confirm the hybrid matrix’s feasibility. Hybrid composites share similar applications as the PMCs; however, due to their higher costs, their use is restricted.

Ceramic Matrix Composites (CMCs)

The composite of materials like silicon carbide, aluminum, boron carbide, and carbon makes the ceramic matrix. Then, this matrix is reinforced with strong fibers to form CMCs. These ceramic matrices offer extreme corrosion and temperature resistance as well as great wear properties. However, ceramics are usually brittle whenever they are not reinforced. Adding silicon carbide, carbon, or alumina filters can make the material more serviceable and counter its brittleness.

CMCs are useful in making blades of gas turbines, heat exchangers, and aerospace/rocket components. These composites are very expensive and they are quite brittle, which makes their use limited. However, this field is one of great research and properties keep improving.

Natural Fiber Composites (NFCs)

The use of natural fibers is becoming a trend in the manufacture of composites. This reduces the impact these materials have on the environment during their use. Some natural fibers including wood, jute, cotton, and flax are important in different ways.

Natural fibers that are bonded with resin are useful in manufacturing the interior panels of an automotive. These fibers undergo compression molding to take a specific shape, after which they are upholstered into leather or plastics for the final surfacing. 

To ensure greater strength and create a wood effect, you can add wood fibers to polymers. Also, skateboard decks utilize natural fiber reinforcements extensively in polyester resin matrices.

Carbon Fiber Reinforced Polymers (CFRPs)

These form a subset of the polymer matrix composite. They are specific to polyester and epoxy-bonded carbon fibers. Hand lay-ups require the use of carbon fiber as the woven roving, using weave patterns for different stress distribution and loading types. 

Here, you impregnate the fibers with the thermally-activated resins. This lays up the flexible material and then it is compressed to help liquefy and cure the resin, which produces a rigid result. It is also possible to pultrude carbon filters with different polymers to create continuous CFRP lengths in different complex sections.

Aramid Fiber Reinforced Polymers (AFRPs)

These form another group of the polymer matrix composites, which utilizes aramid as its reinforcer. The aramid fiber components are useful in high-impact applications. Generally, the aramid is useful as a woven fabric. Additionally, they are pre-impregnated with polyester and epoxy resins. 

Another composite here is the aramid/paper honeycomb material, which are useful in the low-profile flooring panels – which are epoxy bonded and layered using aluminum sheets.

Functionally Graded Composites (FGCs)

Functionally graded composites form a part of all types of composites. In this composite material, you can modify the constituent parts in the application via the structure performance. When the properties gradually transit, they are useful in avoiding stress concentrations. 

Also, the functional grading could be as easy as altering or adding the fiber content at an elevated stress point; progressive hybridization to help impact resilience in some regions; changes in the weave pattern in the roving to change the load distribution.

FGCs are useful in making more resilient and lighter spacecraft and aircraft components like rocket nozzles and turbine blades.

Macro Composites 

Unlike micro or nano- forms, macro composites combine the constituent materials in larger form. You can see the layers or structure clearly. They are thicker and can accommodate different types of material at different areas of a single sheet or bar.

The micro types are used in high-performance applications like structural items and cargo accessories.  Consequently, they can be actually customized to fulfill some specific requirements, such as mechanical strength and flexibility.

What are the Industrial Applications of Composite Materials?

Below are some of the areas where composite materials are applicable

• Plywood during construction
• Glass-reinforced plastic to ensure high-strength molding
• Boat hulls, kayaks, aircraft skins, and motorcycle fairings
• Spectacle frames (usually mold plastic over a specific metal structure)
• Carbon fiber (epoxy-bonded) in fishing rods
• Ferroconcrete useful for construction purposes
• Flooring of aircrafts

Conclusion

RapidDirect has vast experience in conducting research and is involved in the development of composite materials. Our expertise encompasses all areas of using composites, which include the design, modeling, processing, NDT, repair, joining, testing, and more.

Furthermore, our dedicated team for composite machining handles your project to meet all designed specifications and requirements. Our custom tooling approach for CNC machining services allows us to handle carbon fiber, polymer matrix, kevlar, and other tough composites. So, send us your design if you are looking for high-performance parts.

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