Accelerated aging failure guide

We have more and more options when choosing a product on the market. We have all faced the difficult decision to choose between different brands or even between different models within the same brand. This wide range of possibilities makes manufacturers seek to differentiate their products from the competition.
There are many key aspects that can differentiate a product from its competitors: price, size, design, quality or durability. Of all these aspects, durability is one of the most important for many customers when selecting one product or another. Nobody likes that a product we just bought deteriorates soon or that it does not last as long as we had planned.
Within this framework, in today’s blog we are going to talk about accelerated aging, which is one of the most important topics in our area of forensic engineering. Specifically, we will tell you how this aging occurs in some products or materials, what agents cause it and, most importantly, how to solve this type of problem.

What is and how is accelerated aging generated in a product?

In general, accelerated aging failures occur due to the low resistance of a material, or a product, to the action of a certain external agent. A typical example of this type of aging is the fading of billboards on the streets. In this case, the ultraviolet (UV) rays of the sun degrade the pigments of the inks or paints, generating a loss of color, which is a sign of aging or degradation.
This type of accelerated aging is one of the easiest to recognize with the naked eye, however, there are numerous cases of accelerated aging that are the main reason why a product fails, loses some of its main properties or aesthetic quality.
Therefore, knowing the origin of accelerated aging is the first step to find the correct solution, in such a way that the life of any material or product can be extended to increase its value.

What types of aging can appear in materials or products?

Accelerated aging can occur in many forms, some are easily detectable, such as advertising signs that degrade in the sun, while others are not detected with the naked eye. Here are some of the most common types of accelerated aging:

• Discoloration. As we anticipated, the discoloration of a material is one of the most common and most important accelerated aging, since it generates a loss of colour, a very negative effect on the quality of the product. For this reason, discoloration is an accelerated aging very easy to detect, as it directly affects the appearance and design of the product, which is increasingly important. An example of this type of aging would be the loss of colour in plastic materials, the discoloration of paintings on facades, or the yellowing of the silicone covers of our mobile phones.

• Loss of mechanical properties. Unlike the previous one, the loss of mechanical properties is an aging that is not observed with the naked eye. However, this can become a significant problem since, if the loss of mechanical properties of a product occurs without having detected it, the consequences can be much more serious than in the case of discoloration, which only affects the aesthetic aspect, but may have consequences that affect the safety of the product and therefore of the person. Some of the most typical cases of this type of accelerated aging are the appearance of microcracks in metals, a consequence of fatigue, the increase in plasticity, the reduction of the tensile strength in plastics or the loss of hardness in surfaces.

• Rust or Corrosion. The low resistance of a material to humidity or direct contact with water can cause significant problems of accelerated aging due to oxidation or corrosion. Corrosion can be detected with the naked eye and can pose great safety risks in facilities. The most typical examples of accelerated aging due to corrosion occur in metal parts that are found in atmospheres with high water vapor or metals that have to be submerged in salt water. In this case we would also be facing not only an aesthetic failure but also a product safety.

• Adhesion problems. As we’ve seen on other blogs, paint or coating adhesion problems are very common in some products. In this case we will focus on how the accelerated aging of the adhesion between the paint or coating and the material occurs. This accelerated aging occurs if the adhesion is not sufficiently resistant to the conditions to which the product is subjected. The main examples of accelerated adhesion aging would be the appearance of aesthetic defects in paints or the loss of protection and functionality of a coating on a material.

• Loss of gloss. Like discoloration, loss of gloss is a very common fault with some metals or plastics. This accelerated aging can be easily appreciated and is usually caused by the change in roughness of a surface. Being an aesthetic element, the loss of gloss can greatly affect the quality of a product. A clear example of this type of accelerated aging is the scratching of metals in aesthetic areas of electrical appliances, mobile phones or jewelry.

These are some of the more common accelerated aging failures, however there are many more types. Each of them must be studied in detail to know the origin of the problem and to be able to determine which is the best solution.

External agents that generate accelerated aging failures

Accelerated aging failures are usually caused by the action of an external agent that degrades some of the components of the material or product. Next, we indicate which external agents are the most common:

• Solar radiation. The action of the sun, more specifically ultraviolet (UV) radiation, is one of the external agents with the greatest influence when it comes to generating accelerated aging of a product or material. There are different types of ultraviolet rays (UV-A, UV-B or UV-C), which affect materials in different ways. This radiation usually affects materials with paints, inks or pigments, leading to loss of colour, or it can even generate problems of loss of mechanical properties.
• Temperature. Extreme temperatures act as an accelerator of any aging process in materials and products. In general, high temperatures can cause degradation of plastics, corrosion of metals or even loss of adhesion of paints or coatings. Low temperatures usually affect polymers due to their embrittlement effect.
• Thermal shocks. Continuing with the temperature, sudden changes in temperature, or thermal shocks, can also cause serious accelerated aging problems. Many materials are prepared to withstand extreme temperature conditions, however, sudden changes do not support them well. This can lead to mechanical problems or cracks.
• Humidity. Humid environments or direct contact with water can be a big problem for some products that are not prepared for it. These types of conditions usually generate problems of discoloration, corrosion, oxidation or loss of functionality of some coating.
• Contact with chemical agents. Many products degrade when in contact with cleaning agents, air fresheners, oils, or any other chemical compound. This can lead to aesthetic defects, or serious corrosion problems, which lead to accelerated aging of the material.
• Mechanical stress. The mechanical stress to which some elements or materials are subjected can also be an important external agent when it comes to generating accelerated aging. This can cause mechanical problems in the parts, or the appearance of cracks.

In addition to the effect that they produce by themselves, these agents can be combined with each other, giving rise to very serious problems for the materials that make up a product.
The main problem with the aging of a product is the time it takes to manifest itself, which prevents immediate solutions from being taken. For this reason, previous experience in this type of case and the performance of accelerated aging tests in the laboratory is very important.

How to solve an accelerated aging problem

At ATRIA we have experience in solving this type of accelerated aging failure. As we anticipated, in each case the external agent that is causing aging must be found and the component that is failing must be detected. Next, we indicate ATRIA’s work methodology in this type of projects:

1. Characterization of the failure. The first step in detecting the source of an accelerated aging failure is to characterize the failure. Through this characterization it is possible to determine the component that is failing and the external agent that degrades it. To carry out this first step, ATRIA has characterization equipments that allow us to understand the problem and propose a series of improvements to solve it.2. Proposal for improvement. Once the failure is known, a series of improvements will be proposed to protect the component that is failing from the external agent that is causing the problem. Some examples of improvement are:

• Replace or modify the pigments to avoid their UV degradation.
• Use additives that protect materials from external agents.
• Substitution of materials with better resistance to external agents.
• Use protective coatings on the material to reduce the degradation caused by the external agent.
• Redesign the material to reduce mechanical stress
• Use of protective coatings for painting or coating.
• And many more!

3. Accelerated aging test

. Finally, to know which solution behaves best, all of them must be tested in accelerated aging equipment. This step is essential, since aging problems can take days, months or years to appear. Using accelerated aging equipment we can simulate years in days, in such a way that the effectiveness of any solution can be verified in short periods of time. Some of the equipment we have to carry out these tests:

• Climatic chambers, which allow us to expose the material or product to different conditions of temperature and humidity in a controlled way.
• Thermal shock chamber, capable of subjecting any material to sudden changes in temperature in an accelerated and controlled manner.
• Aging cabin accelerated by artificial or ultraviolet light. This equipment makes it possible to control the effect that a certain light, with different wavelengths, exerts on materials. In addition, the humidity and the temperature of the cabin can be controlled, which allows to control several variables at the same time.
• Saline mist cabin, with which the corrosion process of parts can be accelerated under extreme conditions of humidity and salinity.
• Standardized abrasion equipment which allows to subject materials or coatings to an effect controlled abrasion and compare result.

All these teams can work under certain standards or can be programmed to carry out personalized tests. In future blogs we will tell you in more detail how these teams work and the tests that can be carried out with them.
Do you want to solve a problem of accelerated aging of any of your products? Contact us!