What is Composite Material?
A composite material is a combination of two materials with different physical and chemical properties. When they are combined they create a material that is specialized 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.
These constituent materials have notably dissimilar chemical or physical properties and are merged to create a material with properties, unlike the individual elements. Within the finished structure, the individual elements remain separate and distinct, distinguishing composites from mixtures and solid solutions.
Typical engineered composite materials include:
- Reinforced concrete and masonry
- Composite wood such as plywood
- Reinforced plastics, such as fiber-reinforced polymer or fiberglass
- Ceramic matrix composites (composite ceramic and metal matrices)
- Metal matrix composites
- and other advanced composite materials
There are various reasons why new materials can be favored. Typical examples include materials that are less expensive, lighter, stronger, or more durable when compared with common materials.
More recently researchers have also begun to actively include sensing, actuation, computation, and communication into composites, which are known as robotic materials.
Composite materials are generally used for buildings, bridges, and structures such as boat hulls, swimming pool panels, racing car bodies, shower stalls, bathtubs, storage tanks, imitation granite, cultured marble sinks, and countertops. They are also being increasingly used in general automotive applications.
The most advanced examples perform routinely on spacecraft and aircraft in demanding environments.
What Are Composites?
A composite is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a material with properties, unlike the individual elements.
Simply put, composites are a combination of components. In our industry, composites are materials made by combining two or more natural or artificial elements (with different physical or chemical properties) that are stronger as a team than as individual players.
The component materials don’t completely blend or lose their individual identities; they combine and contribute their most useful traits to improve the outcome or final product. Composites are typically designed with a particular use in mind, such as added strength, efficiency, or durability.
What are composites made of?
Composites, also known as Fiber-Reinforced Polymer (FRP) composites, are made from a polymer matrix that is reinforced with an engineered, man-made, or natural fiber (like glass, carbon, or aramid) or other reinforcing material.
The matrix protects the fibers from environmental and external damage and transfers the load between the fibers. The fibers, in turn, provide strength and stiffness to reinforce the matrix and help it resist cracks and fractures.
In many of our industry’s products, polyester resin is the matrix, and glass fiber is the reinforcement. But many combinations of resins and reinforcements are used in composites and each material contributes to the unique properties of the finished product: Fiber, powerful but brittle, provides strength and stiffness, while more flexible resin provides shape and protects the fiber.
FRP composites may also contain fillers, additives, core materials, or surface finishes designed to improve the manufacturing process, appearance, and performance of the final product.
Natural and synthetic composites
Composite materials can be natural or synthetic. Wood, a natural composite, is a combination of cellulose or wood fiber and a substance called lignin. The fibers give wood its strength; Lignin is the matrix or natural glue that binds and stabilizes it. Other composites are synthetic (man-made).
Plywood is an artificial composite that combines natural and synthetic materials. Thin layers of wood veneer are adhesive together to form flat laminate sheets that are stronger than natural wood.
Are plastics composites?
Not all plastics are composites. In fact, most of the plastics used in toys, water bottles, and other familiar items are not composites. They are pure plastics. However, many types of plastics can be reinforced to make them stronger. This combination of plastic and reinforcement can create some of the strongest, most versatile materials (for their weight) that technology has ever developed.
Polymer resins (such as polyester, vinyl ester, epoxy, or phenol) are sometimes referred to as plastic.
People have used composites for thousands of years. 3400 BC The first man-made composites were made by the Mesopotamians in Iraq. The old society glued strips of wood on top of each other at different angles to make plywood.
Following this, the Egyptians began around 2181 BC to make death masks from linen or papyrus soaked in plaster. Later, both societies began to reinforce their materials with straw to strengthen mud bricks, pottery, and boats.
In 1200 AD, the Mongols began constructing compound arches, which were incredibly effective at the time. These were made from wood, cattle tendons, horn, bamboo, bone, and silk bonded with pine resin.
After the industrial revolution, synthetic resins took on a solid form through polymerization. In the 1900s, this newfound knowledge of chemicals led to the manufacture of various plastics such as polyester, phenol, and vinyl. Then the development of plastics began, Bakelite was made by the chemist Leo Baekeland. The fact that it did not conduct electricity and was heat-resistant meant that it could be widely used in many industries.
The 1930s was an incredibly important time for the advancement of composites. Glass fiber was introduced by Owens Corning, who also founded the first fiber-reinforced polymer (FRP) industry. The resins developed during this period are used to this day, and unsaturated polyester resins were patented in 1936. Two years later, more powerful resin systems became available.
The first carbon fiber was patented in 1961 and then became commercially available. In the mid-1990s, composites became increasingly popular in manufacturing processes and construction because of their relatively low cost compared to previously used materials.
The composites on a Boeing 787 Dreamliner in the mid-2000s substantiated their use for high-strength applications.
Different Types of composite materials
Some common composite materials include:
- Ceramic matrix composite: Ceramic spread out in a ceramic matrix. These are better than normal ceramics as they are thermal shock and fracture resistant
- Metal matrix composite: A metal spread throughout a matrix
- Reinforced concrete: Concrete strengthened by a material with high tensile strength such as steel reinforcing bars
- Glass fibre reinforced concrete: Concrete which is poured into a glass fibre structure with high zirconia content
- Translucent concrete: Concrete which encases optic fibres
- Engineered wood: Manufactured wood combined with other cheap materials. One example would be particle board. A speciality material like veneer can also be found in this composite
- Plywood: Engineered wood by gluing many thin layers of wood together at different angles
- Engineered bamboo: Strips of bamboo fibre glued together to make a board. This is a useful composite due to the fact it has higher compressive, tensile and flexural strength than wood
- Parquetry: A square of many wood pieces put together often out of hardwood. It is sold as a decorative piece
- Wood-plastic composite: Either wood fibre or flour cast in plastic
- Cement-bonded wood fibre: Mineralised wood pieces cast in cement. This composite has insulating and acoustic properties
- Fibreglass: Glass fibre combined with a plastic which is relatively inexpensive and flexible
- Carbon Fibre reinforced polymer: Carbon fibre set in plastic which has a high strength-to-weight ratio
- Sandwich panel: A variety of composites that are layered on top of each other
- Composite honeycomb: A selection of composites in many hexagons to form a honeycomb shape.
- Papier-mache: Paper bound with an adhesive. These are found in crafts
- Plastic coated paper: Paper coated with plastic to improve durability. An example of where this is used is in playing cards
- Syntactic foams: Light materials created by filling metals, ceramics or plastics with microballoons. These ballons are made using either glass, carbon or plastic
Benefits Of Composites
Composites have permeated our everyday lives: They are used in the cars we drive, golf clubs we swing, pipes that remove wastewater from our neighborhoods, and much more. Some applications, such as rocket ships, probably wouldn’t get off the ground without composite materials.
Composites offer many benefits. Key among them are strength, lightweight, corrosion resistance, design flexibility, and durability.
- Strong. Per pound, composites are stronger than other materials such as steel. The two primary components of composites – fibers and resins – contribute to their strength. Fibers carry the load, while resins distribute the weight throughout the composite part as required.
- Lightweight. Composites are light in weight compared to most woods and metals. But why is lighter better? Lower weight contributes to fuel efficiency in cars and airplanes. And lighter objects, ranging from utility poles to bridge decks, are easier to transport and install.
- Resistant. Composites resist damage from weather and harsh chemicals that can eat away at other materials. That makes them good choices for applications that face constant exposure to salt water, toxic chemicals, temperature fluctuations and other severe conditions.
- Flexible. A wide range of material combinations can be used in composites, which allows for design flexibility. The materials can be custom tailored to fit unique specifications of each application. Composites also can be easily molded into complicated shapes.
- Durable. Simply put, composites last! Structures made with composites have a long life and require little maintenance. Many products made with composites, such as boats, have been in service for more than half a century.
Why use Composites?
Weight saving is one of the main reasons for using composite materials instead of conventional materials for components. While composites are lighter, they can also be stronger than other materials. For example, reinforced carbon fibers can be up to five times stronger than 1020 grade steel and only one-fifth the weight, which makes them perfect for structural purposes.
Another advantage of using a composite material over a conventional type of material is the thermal and chemical resistance as well as the electrical insulation properties. Unlike traditional materials, composites can have multiple properties that are not often found in a single material.
Fiber-reinforced composite materials such as fiber-reinforced plastic (GRP composite materials) are increasingly being used in the development and manufacture of end products for marketing.
Examples of Composite Uses:
- Electrical equipment
- Aerospace structures
- Pipes and tanks
- Homes can be framed using plastic laminated beams