▶ Introduction to Ozone
Ozone, a gas that appears light blue and has a special odor at room temperature and pressure, is known for its excellent oxidizing ability and bactericidal effect. As a strong oxidant, ozone has a universal corrosiveness to metals, and almost all metals will be corroded in an ozone environment except for gold and platinum, which have a relatively small impact. Especially aluminum, zinc, and lead, they rapidly oxidize when in contact with ozone. However, iron alloys with higher chromium content have higher resistance to ozone corrosion.
For non-metallic materials, ozone also has strong corrosiveness. When designing ozone generating equipment, ordinary rubber is not suitable as a sealing material due to its susceptibility to corrosion, and silicone rubber or acid resistant rubber with stronger corrosion resistance should be selected.
▶ Ozone testing equipment
Test box: a device used to simulate specific environmental conditions.
Ozone generator: produces a specific concentration of ozone.
Ozone measuring device: used for monitoring and controlling ozone concentration.
▶ Principle of ozone aging test
The sample is placed in an environment that maintains a constant temperature and ozone concentration. Check whether there are cracks or crack propagation in the sample at set time intervals. The experiment can use the following three inspection methods:
After exposure under specified time and strain conditions, check whether the sample has cracks and measure the degree of cracks if necessary.
Measure the shortest time it takes for a sample to start cracking under any specified strain conditions.
Determine the maximum critical strain at which the sample does not crack for any specified exposure time.
▶ Ozone aging test method
Although ozone is a gas with extremely low levels in the atmosphere, it is the main factor causing rubber material cracking. The tolerance of different rubber materials to ozone varies significantly due to differences in ozone concentration and environmental temperature. By simulating and enhancing the ozone conditions in the atmosphere in a test chamber, the sample is exposed to an environment containing a constant concentration of ozone, and its cracking condition is regularly checked.
▶ Ozone aging test standard
GB/T 7762-2014: Rubber, vulcanized or thermoplastic - Static tensile test for resistance to ozone cracking
DIN ISO 1431-1-2011: Test method for ozone cracking resistance of vulcanized or thermoplastic rubber.
VW 2.8.1: Volkswagen standards, involving requirements and tests for rubber materials.
QC/T 17-1992: General rules for weather resistance testing of automotive components.
▶ Determination of ozone aging results
The test results should clearly report whether the sample has cracks. If cracks appear, the degree of cracking needs to be evaluated, which can be demonstrated by describing the characteristics of the cracks or by taking photos. In addition, it is necessary to determine the maximum strain at which the sample does not crack and the minimum strain at which cracking occurs after the specified exposure time, in order to define the critical strain range.
