Accelerated Aging Testing

Accelerated aging test services are offered at Micom Laboratories to a wide range of industries.  Essentially, most of what we do answers one of the three following questions:

• What happened to my product/material/assembly?
• What will happen to my product/material/assembly?
• How strong is my product/material/assembly?

What is accelerated aging used for?

Accelerated aging is used to simulate real-time aging under controlled, yet accelerated conditions. Aging methods use one or more of the following aging processes: heat, cold, humidity, sunlight, vibrations, corrosive environment, cyclical loads and many more. In many cases, more than one of the aging processes is applied simultaneously.

How We Accelerate A Product’s Aging Process

A product’s aging process can be accelerated in the laboratory in various ways depending on the material/product being tested, the intended use, and the ambient conditions while the material/product is in use. Below are the various Accelerated Aging processes Micom offers:

When doing this type of testing, it is important to understand the product characteristics, the normal use conditions, what constitutes foreseeable abuse, and the product’s life expectancy. In all cases, our customers want to have their answers yesterday.  However, to have a good test plan one must be careful not to expose the product to be tested to conditions that are such that abnormal aging processes start occurring.

Basic Rules

Increased temperatures are often by themselves but often in conjunction with other accelerated aging processes (humidity, UV, electrolytes/salt solutions (corrosion)). Indeed, heat often works synergistically with other aging processes.

Temperature

Nonetheless, there are some basic rules to be followed in all aging test procedures.  Except for freeze-thaw cycles that assesses the impacts of phase changes, all aging processes increase as a function of the ambient temperature.  This acceleration process is governed by Arrhenius’s equation:

Where:

T_AA: Accelerated aging temperature (^oC)

T_RT: Ambient temperature (^oC)

Q₁₀: Rate of the chemical reaction, typically 2

In layman’s terms, any chemical reaction will double its rate with each 10 °C increase.  This is why corrosion and UV aging, for example, are both done at temperatures above room temperature. Conversely, excessive temperature exposure is not recommended. Indeed, beyond a certain point, the molecules of a given material can be supplied with sufficiently high levels of activation energy that will allow them to create some chemical reactions that would not naturally occur even over long periods of time or extremely adverse conditions.  Furthermore, in many accelerated aging processes, there is an asymptotic behavior for organic molecules i.e.: beyond a certain temperature there is no significant gain; only risk.

Figure #1a: Arrhenius’s Law – Accelerated Aging Curves
Arrhenius’s law is general in nature, and it assumes the general case where the aging rate doubles every 10^oC increase. This ideal case would correspond to curve Q10=2 above.  Should this be the case, and should you wish to age your products at a temperature of 45 ^oC, you would need a 10-week aging process to simulate one year of real-life aging.  The accelerated aging factor is not always “2”.  If the aging factor is known, then the simulation can be adjusted accordingly.  For example, should it turn out that the material being tested has an accelerated aging factor of 3 (q10=3 above); for the same aging temperature of 45 ^oC, the number of normal use weeks of aging would be 4 instead of 10.
Heat aging is often done to ASTM D3035 and ASTM F1980.