silicone usage expanding in european automotive applications.

by:Keyuan     2020-06-08
Over the past two decades, the use of silicone in automotive applications in Europe has been expanding, and the strong combination of environmental, economic and aesthetic pressures has forced the performance requirements of elastomer in American cars to rise steadily.
Part of this pressure is the result of an environmental control device that significantly affects the operating temperature of the engine, exhaust system, and drive
Therefore, the train with lower temperature and lower temperature is stably eliminated
Performance Products.
And the ongoing warranty war between competing car manufacturers in the United StatesS.
The market also puts forward higher requirements for the physical and mechanical properties of elastic parts.
A consequence of this drive for a higher version
At least in the field of elastic materials, performance materials are the focus of competition among automakers in the United States. S.
The use of silicone materials on the market has increased significantly.
For example, almost all engine washers in the United States todayS. -
The car made is silicone of one kind or another.
Silicone has been used in the automotive industry for nearly 30 years, in ignition cables and boots, shaft seals, self-
Eye-catching and adhesive sealant for air-guiding connectors.
The series of inorganic polymers is known for providing outstanding performance in some of the industry\'s most demanding applications.
However, the price premium for this level of durability and reliability tends to hinder their use in terms of cost
Sensitive applications.
However, as the automotive industry changes globally and the performance requirements of all automotive materials become increasingly demanding, silicone polymers are becoming the only material that can handle the job.
However, the rubber specifications and usage trends in the European automotive industry generally follow the same pattern as in the United StatesS.
They are doing this much slower and less aggressive.
Therefore, the use of flexible materials in the market is still mainly composed of lower
Performance of organic materials.
But this is expected to change rapidly over the next three to five years.
Keeping up with the changing market new environmental regulations may be the biggest power for European automakers to steer silicone elastomer for seals, washers, hoses, shields and many other related applications.
The current environmental laws in Europe are as diverse as the languages and geography of the continent.
However, when most Western European countries plan to unite in the European Community, the situation will change by 1992 (EC)
A comprehensive economic entity with no trade barriers and tariffs between member states.
While public attention to the event is primarily focused on issues such as trade opportunities and common European currencies, the impact of harmonization on product and environmental standards may be equally important.
On the environmental front, it is expected that EU countries will eventually and firmly establish uniform regulations on automobile emissions to help protect the environment and its fragile infrastructure.
The regulations are expected to be similar to those of the United States. S.
, Forcing the use of catalytic converters and other environmental controls, which were more or less optional before.
They may even ask for a more rapid transition to the top. alcohol-
Content fuel, widely used in South America, is now selectively tested in the United StatesS.
In addition, the development of carbon fluoride (CFC)-free heat-
Air exchange products for cars
Air conditioning system.
Each of these changes
More stringent emission control, alternative fuels and alternative heat
Exchange Materials
The engine temperature will be increased, new chemical environments will be introduced, and additional requirements will be made for washers, seals, hoses, diaphragm, fuel lines, syringes and exhaust system components.
These new requirements, in turn, will drive carmakers competing in Europe to take advantage of higher
Performance Materials.
But environmental control is not the only factor that works here.
Design changes (
Usually led by Europeans)
New global emphasis on quality, potential European warranty wars and other new technologies will also drive these shifts in silicon polymers.
Environmental control and heat problems in the United StatesS.
In the past few decades, more and more car operating temperatures have been considered to be caused by more stringent environmental controls, which has led to market penetration of organic silicone rubber. Engine down-
The 70-year scale and strict EPA emissions and fuel economy restrictions began to heat up.
The lateral installation and turbocharging of the engine also led to the temperature rise of some models.
The environmental control makes the exhaust system components run hotter, causing more and more heat to radiate upwards to the passenger compartment (
Especially in the area above the catalytic converter).
This heat is considered to be an excess tax on the air conditioning system and causes the interior carpet to fail prematurely because the backing and foam start to break, not because of wear, but because of degradation.
Now, new environmental controls are starting to work, which will make the working temperature higher and affect the global material specifications.
Proposed changes and flexibility for Gasohol-
Fuel Vehicles, which can be adjusted from the tank to various fuels, from gasoline to methanol to ethanol, to a mixture of three fuels, pose some engineering challenges to the material and design community.
Because the energy density of gasoline is about half that of gasoline, the car using this fuel needs a much larger tank, usually twice that of the current tank, in order to reach the same range.
Since gasoline has a higher Cetane value than gasoline, the engine must operate at a higher compression ratio in order to effectively burn this fuel.
Unfortunately, gasoline will not run at such a high compression ratio.
So temporary flexibility
Fuel Vehicles must compromise the efficiency between the two fuels in order to deal with the fuel and mixture between the two.
The volatility of alternative fuels is low, which means it is more difficult to start using in cold weather, so special fuel syringes and high
Energy ignition systems need to be developed.
In the safe area, unlike gasoline, gasoline can form a flammable mixture in the fuel tank, so special fire needs to be used
The resistance system around the tank.
In addition, the alcohol flame is almost invisible and the smell of its steam is minimal.
Therefore, as in natural gas, additives need to be added to warn of leaks or fires.
Gasohol not only makes the engine run hotter, but also needs to use higher-
Temperature material, but it also represents a new chemical environment that is not good for many traditional automotive materials.
Because gasoline softens, dissolves or corrupts some plastics, rubber and metals currently used as fuel tanks, fuel lines and fuel injection seals, pipes, hoses and separators, alternative materials may need to be considered in many application areas.
For example, since the ethanol mixture constitutes a new chemical environment, it may be necessary to switch to a stainless steel gas tank.
In addition, although better fuel is provided by fluorine-hydrocarbon rubber
In straight gasoline, the expansion performance is better than that of fluorine silicone rubber, and as the percentage of alcohol in the fuel mixture increases, the performance of many fluorine-hydrocarbon rubber decreases significantly.
Since fluorine-silicone rubber provides enough expansion resistance in any combination of gasoline-
Alcohol mixture, thanks to the excellent low fluorine Silicon offers
Temperature performance, with the widespread use of alternative fuels, it is expected that these silicone polymers will replace organic rubber.
A similar situation exists with alternative refrigerants.
As global concerns about the greenhouse effect and ozone consumption become stronger and stronger, the development of effective, non-
Carbon Fluoride (CFC)-
When air-conditioning systems become an increasingly popular choice for cars, especially in Europe.
It is reported that the first commercially available product is less efficient than the CFC refrigerant currently used and is likely to affect the following
Use of Hood materials.
The condenser using this new refrigerant requires higher air flow and the working pressure of the alternative system is estimated to be 10-
12% higher than existing technology.
Higher pressure and hotter temperatures are likely to require higher-
Handling performance materials for new coolant.
Similarly, the new chemical environment may present challenges to the materials for the pre-treatment of fluorine-chlorine-carbon coolant.
In the United States, changes in design have also led to higher operating temperatures. S. and abroad.
Today\'s smoother, windswept lines of more aerodynamic cars force the front end to become lower and more crowded, reducing the flow of air to the engine block when the hood temperature rises.
At the same time, the use of window glass has increased, especially the popularity of high
The tilting shape of the windshield further promotes the acquisition of solar energy, bringing the instrument panel close to heat-
Deformation temperature of some plastics.
The rise of indoor temperature not only brings more pressure to the air-conditioning system, but also the air-conditioning system will cause the temperature to rise further, and the rise of this temperature needs to use a higher temperature.
Performance Polymer, not only in the instrument
The panel housing and support structure, but also in the pipeline works.
In fact, the dashboard pipeline is a promising application area for silicone foam and pipelines.
Dealing with hot issues: as a few of the following solutionshood, drive-
Train and exhaust
With the increasingly harsh system environment, especially in the hot areas of the engine, the role of Silicone elastic materials is becoming more and more important.
In Figure 1, the progress of the deficiencies
Hood temperature and elastic life, time (in hours)
The elongation of materials in general categories will be reduced to 50%.
As the temperature rises, elasticity
The life-span capacity of organic elastomer is rapidly decreasing, and there are few materials with sufficient performance.
Since there is no sign of a reduction in the high temperature problem, new approaches are being sought to deal with the situation more effectively.
One of the methods is to use shielding to isolate heat around hot spots and to protect more sensitive hot parts.
In applications where shielding is not simple enough, the manufacturer\'s transaction price will be higher --
Higher performance-
Temperature material.
The material that can be foamed has better insulation performance and lighter weight, and the elastic foam can not only buffer the components, but also better handle vibration and abuse.
However, as temperatures rise, less flexible foam is a suitable candidate, especially since many of them do not provide enough heat
Aging properties.
Instead, they harden and shrink after repeated heating/cooling cycles, moving away from the parts they are designed to be shielded, often resulting in more noise than when originally designed to stop and
For silicone foam, the field of thermal shielding is a very promising one.
These lightweight, elastic rubber have excellent thermal properties
Aging properties, very extensive temperature capabilities and non-
Halogen flame retardant. Medium-and low-
The density versions of these products are expected to achieve significant penetration in numerous automotive and public transport applications.
For example, on many vehicles, given that designers can currently obtain more stringent, more odd-shaped space requirements, and the almost universal desire to reduce the weight of passenger cars, plastic fuel tanks are now necessary.
However, the material used to shape the gas tank
Deflection temperature below 200 [degrees]
F. Close to the exhaust system that may exceed 800 [degrees]
F worries many people.
Early attempts to shield plastic gas tanks focused mainly on corrugated aluminum covers.
However, the function of aluminum is more as a radiator than a heat shield, and it is very troublesome to install around a tank with a strange shape.
Therefore, a kind-
As a replacement, density, elastic silicone foam and aluminum foil are being evaluated.
The lightweight foam/foil composite emits heat on its source head to keep the tank cool.
It can easily be covered around the uneven outline of the tank, and each vehicle can reduce the weight by a few pounds.
This same flexible silicone foam/foil composite is also considered to be used as a liner under an internal carpet, especially on a catalytic converter, as well as on a firewall, inside and around the engine.
Heat of materialand sound-
This change is driven by shielding properties, light weight and flame retardant properties.
Other areas of high-
Temperature capacity of silicone rubber used in exhaust
Pipe hanger and various underneath
Hood connectors and electronic packaging applications. Long flex-
Life at high and low temperatures is a sign of silicone, and is also the reason why silicone rubber replaces organic rubber in applications such as C. V. boots.
As mentioned earlier, silicone elastomer, whether to heat or not
Vulcanization rubber for room
Temperature vulcanization rubber or liquidinjection-
Molded silicone is widely used as engine washers in the United StatesS. -built cars.
Typical applications include washers and water for oil pan and rocker cap-
Pump and crankshaft seals.
In these applications, SEALs using organic elastomer are replaced by silicone seals, not only because the silicone has excellent temperature performance and longevity, but also because it has excellent sealing performance.
Maintain force when exposed to a wide variety of conditions, as well as the convenience of manufacturing and assembly provided by silicone materials.
More applications are expected to spread within 1990s to better control the increasing heat issues both under the hood and inside and outside the exhaust system.
As European manufacturers face higher operating temperatures, they will also be forced to upgrade their rubber to meet stricter performance requirements.
In addition, the trend of a more efficient and modular engine worldwide also opens up opportunities for silicone washers on plastic carriers and/or metal covers and carriers. These one-
Part systems also help automate manufacturing and assembly.
How design changes affect material selection, while many design changes affect material use due to their contribution to vehicle heat, other design changes also affect material selection, but for different reasons.
For example, the use of plastic in body panels and bumper systems has increased, driving the development of alternative fastening systems.
Typically, the most cost-effective, efficient and durable way to connect plastic parts to yourself or different materials is to use adhesive bonding.
Since plastics are generally not as strong as metal, engineers often have to design closer to their yield strength, otherwise stress concentration caused by mechanical fastening systems can cause premature failure of parts.
However, adhesive fasteners that are chemically compatible with the substrate not only eliminate the common stress concentration of mechanical fasteners, but they also provide a more uniform stress distribution on the wider surface area of the part.
This, in turn, gives engineers more freedom to optimize the design of the parts, as there is no longer a need to maintain a low stress level.
In addition, because of their application methods, the adhesive also provides the advantage of improving aesthetics.
The outer surface of the adhesive assembly can be smooth, uninterrupted and beautiful.
The deformation caused by point fastening or vibration welding is eliminated, reducing or even eliminating the cost and time of additional finishing operations.
While many organic adhesives compete with silicone in this field, the elastic properties of Silicone Adhesives/sealant and their excellent temperature capabilities in a wider range are further accounted --
Transfer through silicone adhesive.
The latest and most promising application of Silicone Adhesives is in the field of bumpers. Several room-temperature-vulcanizing (RTV)
Elastic silicone,
Part of the adhesive and two-
Part of the adhesive, which has been successfully used to inject two types-and blow-
Molded thermal bumper system.
These elastic adhesives replace secondary operations such as thermal welding and ultrasonic welding, providing greater energy absorption during impact than mechanical fasteners or organic adhesives, especially at low temperatures (figure 2).
They also help to reduce machinery and heat-
Stress difference between thermoplastic components.
Another advantage of silicone is that it does not become a stress concentrator on the plastic they glue.
They also provide no primerless bonding to bumpers made of thermoplastic alloy resin molding, and more than primer
Partial polyurethane system.
Other silicone RTV adhesives/sealant are widely used in front and rear lighting units to prevent dirt and moisture on glass and polycarbonate lenses and to attach signs and hood trim, rear
Mirrors and side mirrors.
The global quality war, led by Japan, the global automotive industry is engaged in a quality and warranty war that began in the United States. S.
Moved to Europe.
The battle is expected to improve the quality of production for the benefit of consumers, but it may prove costly for automakers who do not improve their quality in advance.
As the warranty time grows longer and more comprehensive, the original equipment manufacturer must decide whether to bear the cost of replacing the lower product or not
Perform the product several times during the warranty period or initially invest in higher performance materials to improve the continuous quality.
There are several inherent problems with using cheaper but lower performance materials.
First of all, the service cost of replacing parts is usually much larger than the cost of the parts themselves.
Too many times consumers return to dealers, even for defective parts that are completely covered, which makes consumers question the automaker\'s commitment to quality.
The consumer may not buy from the car maker any more.
What\'s worse, bad experiences are easier to communicate than good ones, which gives manufacturers a bad reputation among the international public.
Therefore, many manufacturers are learning that in the long run, it is often cheaper to choose more expensive but more effective materials from the beginning.
Air ducts and coolant hoses provide a good example of this trade-off.
The trend of cars getting hotter and turning longer
Between New Times
Car purchase and full reduction-
Gas station (
And maintenance check)
The number of organic rubber belts and hose manufacturers replacing belts and hoses on light trucks and passenger cars has increased dramatically.
But as the temperature rises, organic products will need to change more frequently or will not be appropriate at all.
This replacement problem, coupled with a longer, more comprehensive OEM warranty period, it is predicted that silicone hoses will significantly weaken the market share of organic hoses in air ducts and coolant systems for most passenger cars and light trucks.
Silicone rubber has long been used for molding and straight air-and coolant-
Hose for heavy duty system
Trucks and fleet vehicles.
In fact, there are 17-
Annual performance records for trucks, ambulances, police cars and other heavily used vehicles.
Last year, GE Silicone offered to guarantee that hoses made of its silicone rubber products were installed on OEM vehicles for 10 years or 100,000 miles.
While the initial cost of silicone hoses is three times that of organic hoses, an increase in performance and reliability is expected to significantly offset the spread.
Automakers are also launching a quality war against the interior of the car.
On the new luxury car production line, an automobile manufacturer advertises that both the steering wheel and the gear use a piece of leather.
Therefore, there will be a decline at the same rate.
The same car manufacturer offers a stainless steel exhaust system that is worn out for longer periods of time.
Another car manufacturer is using silicone foam as sound
Deadener on the body pillar to prevent road noise from invading the passenger compartment.
In addition, the use of silicone foam is considered to increase the acoustic effect
Shielding Applications are applied inside the vehicle and under the hood to reduce road noise and enhance quality awareness.
Productivity increases in new plants, although excellent performance may be the main reason for the sharp increase in specifications and use of silicone elastomer in the United StatesS. -
These materials also provide many production benefits for automobile manufacturers.
For example, silicone is chemically inert, biologically compatible, and has no known length
The long-term toxicology effect at that time was handled.
Because they do not need any special treatment other than the general guidelines for handling any industrial material, the production workers do not need to wear special equipment to work safely with them.
Since most silicone materials do not contain organic solvents, there is less risk to the environment and workers.
Solvent-free products can not only reduce inventory, as there is no need to order, track and store any solvent, but also reduce the cost of insurance because the risk of fire and explosion can also be reduced.
Another benefit of silicone elastomer is that there are often many processes for producing parts.
For example, in the air seal and seal area, heating
Cured silicone rubber molding, often falling off
On site, forming a gasket or liquid-injection-
The molding machine can be set to inject silicone into the part to form a mold-in-place gasket.
Silicone RTV adhesive/sealant products can be made by hand or robot-Forming line-in-place gaskets.
Although the seals and washers produced by the three products are slightly different (
Change of mechanical strength)
Manufacturers can choose not only the process that best suits their performance requirements, but also the process that suits their production capacity.
Many of these processes are ideal for automation and automation.
Because most of the production equipment required is simple and easy to use
It is very competitive to increase costs.
Conclusion The global automotive industry is changing and European manufacturers are beginning to find themselves facing the challenge of US and Japanese competitors over the past 20 years.
As Japanese and US automakers work with European manufacturers to avoid being excluded from the EU in 1992, most of their materials and production technologies will be shared.
As a possible result, the use of silicone will increase dramatically in the African continent over the next decade.
The versatility of silicone chemistry, coupled with the reliability, safety and excellent performance of these inorganic materials, has enabled them to penetrate about 40 applications on average in the United StatesS. automobile.
Figure 3 highlights some of the current and potential automotive applications of silicone products.
With the new polymer and processing technology, this number will easily double by 1995.
Silicone will continue to play an increasingly important role in future cars.
Figure 1-
Photo of the \"elastic life\" time required for elongation to be reduced to 50%: Figure 2-
Comparison of energy absorption between silicon and polyurethane10(degrees)
Figure F: Figure 3-
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