How to choose a laboratory UV aging test chamber? -Huaqiang Electronic Network

The ultraviolet aging test chamber uses an ultraviolet fluorescent lamp as a UV light source to perform accelerated aging tests on various materials. The UV-aging test box manufacturer's JR-UV3 UV aging test chamber has ended the long-term monopoly of the US imported UV aging equipment on the domestic market! JR's JR-UV3 performance is stable, the UV aging test box is reasonably priced, welcome to Jerry Contact to discuss the order.

The UV aging test box is also known as the UV aging test chamber, or the UV accelerated weathering test chamber. Applications: Plastics, plastics, paints, chemical materials, engineering materials, building materials, wire and cable, electronic appliances, metal plating, LED photoelectric, display, lighting, crafts, outdoor street lamps, leather materials, PCBA circuit boards, PVC materials , epoxy resin, etc. Through the aging box to simulate the sun, humidity and temperature, the dew of rain water on the material; material aging includes fading, loss of light, strength reduction, cracking, spalling, chalking and oxidation. The UV aging test chamber reproduces damage that may occur in the outdoors for several months or years by simulating sunlight, condensing, mimicking natural moisture, and testing the sample in a simulated environment for a few days or weeks.

Although applications such as heat, humidity and mechanical changes accelerate aging and affect the final properties of the material, the limit on the service life of exposed materials is mainly the ultraviolet radiation of sunlight, so I used it from laboratory aging tests. Various light sources started my discussion.
1. Closed carbon arc lamp This lamp has been used for about 70 years. It was first used in the textile exposure fastness test in 1918 and became the light source of AATCC (American Association of Textile Chemists and Colorists). Many old specifications still require it.
The enclosed carbon arc lamp consists of a group of carbon rods sealed in a gas seal sleeve formed by a metal gas check plate and a borosilicate glass ball. When an electric current flows between the carbon rods, an arc is generated. . Due to the composition of the carbon electrode, the quality of the light produced by it is determined, and any change to the carbon rod will change their spectral energy distribution (SPD), thereby changing the test conditions.
The SPD of a closed carbon arc lamp shows that its main energy is concentrated in three fairly narrow bands. There is also a relatively small energy available below 345 nm, in which the polymer has maximum absorption sensitivity. However, the spectral power distribution of a closed carbon arc lamp is quite different from that of natural sunlight. Carbon arc lamps have neither short-wave ultraviolet radiation in natural daylight nor high-intensity energy in daylight between 400 and 800 nm. Since such lamps are spectrally different from daylight, it is difficult to compare natural weathering and laboratory aging correlations using carbon arc lamps.

Second, the daylight carbon arc lamp The daylight carbon arc lamp is the same as the closed carbon arc lamp. It is the light source used in the week aging test, which first began in 1933. The arc is produced in a pair of three carbon rods, surrounded by eight glass filters, which are used primarily in the coatings industry, and are specified in many specifications.
Due to the defects of the closed carbon arc lamp, the composition of the carbon arc lamp of the daylight carbon arc lamp is changed, so that its SPD is significantly improved similar to the sunlight. However, a large difference between 350 nm and 50 nm compared to the SPD of daylight can still cause poor correlation.

Third, fluorescent UV lamps are theoretically short-wave energy is the main. If it has very little energy, it can cause the material to age. Why not increase this energy significantly and achieve the effect of rapid testing? Comparing the SPD of the FS-40 fluorescent lamp with the SPD of the Florida sunlight, it can be seen that the design standard for increasing the ultraviolet energy is achieved, not only the increase in the UV energy level, but also the spectral range added to the UV energy not found in natural light. This sharp change in energy distribution can cause many products to accelerate damage.
Fluorescent devices can cause unnatural damage due to the presence of radiant energy that is not present in natural daylight when measured on the Earth's surface. In addition to fluorescent light sources, there is no energy above 375 nm, except for very narrow mercury spectral lines, so that materials that are sensitive to longer wavelengths of UV energy may not change as exposed to natural sunlight.
Due to these inherent defects, not only in the spectral distribution, but also other factors beyond control, resulting in irregular results. Jerry Equipment generally does not consider the use of such a light source. We believe its primary use is as an UV screening device, limited to quality control applications.

Fourth, the newest and best source of xenon arc lamps is the xenon arc lamp, which was introduced to the air cooling system for the first time in the 1950s and then used for water cooling in the 1960s. This kind of light source has a great impact on the use of sealed carbon arc lamp accelerated aging test equipment in the original concept period of accelerated aging at the beginning of this century.
Whether it is air cooling or water cooling, xenon lamps have the same basic spectral energy distribution (SPD). The cooling method is different, and the source glass device and structure of the lamp are different. Below we are limited to discussing the water cooling system used in Jerry equipment products.
The water-cooled xenon lamp system consists of quartz, combustion tubes, internal and external filter units and stainless steel assembly components. Stainless steel components allow the parts to be assembled into a single system. After installation, deionized water or distilled water is pumped into the system to cool the tube and absorb long-wave infrared energy. When borosilicate glass is used for internal and external filtering, the xenon lamp system is most similar to natural daylight, and the outer filter glass is changed to soda-lime glass, which is close to the natural daylight filtered through the glass window.

The 2500W and 6000W xenon lamps were originally developed. As the ignition time increases, black deposits form in the electrode area. As the use continues, the deposition expands from the electrode area to the center of the tube. These deposits seriously affect the energy output of the lamp. To shorten the life of the lamp, at that time, the 6000W xenon lamp used at the rated radiation level needs to be replaced every 300~500 hours. Atlas immediately began research to improve the performance of xenon lamps.

In the fall of 1974, under the direction of Mr. APOLLO, a 6500W xenon lamp was developed. This new xenon lamp works in new metal parts. This new metal has no electrode area and eliminates the problem of black deposition. When used with Jerry's equipment's light monitoring system, the 6500W xenon lamp has a service life of more than 1,500 hours, typically up to 2,000 hours. However, the service life of xenon lamps operating under high intensity radiation is affected.

The 6500W xenon lamp is now used in the Jerry equipment SUN series climate aging instrument and fading tester.

Xenon arc lamps were first used in the plastics industry: many specifications such as AATCC, ASTM, ISO and government regulations include it as a use lamp. The textile industry is a traditional user of carbon arc lamps and is now changing their specifications to use xenon lamps. AATCC not only specifies the use of xenon lamps, but also specifies the level of radiation used and the amount of radiation exposure (how many joules per square meter) to produce a desired color change.

Another traditional industry that uses carbon arc lamps is the automotive industry. Recently, the International Industrial Fiber Association IFAI emphasized that the Xenon arc lamp method has been developed as an automotive aging test method for interior equipment and decorative products.

In fact, tests in the JR/SUN/Ci35 and JR/SUN/Ci65 xenon lamp aging instruments proved that many products were up to 98% correlated with the results of natural aging tests exposed at the Florida test site.

We have already discussed the light source, and below we will look at the effects of many other factors besides the light source. These factors should also be considered when we choose an instrument, resulting in a high level of test correlation.

1. Whether the water is directly sprayed (rain), wet, or condensed (dew) is the influencing factor to be simulated in laboratory tests. But unlike temperature or radiation, it can increase water to accelerate photochemical reactions. The humidity of the sample cannot be increased. But what we can do is increase the frequency of dry and wet, wet and dry, and thermal shock cycles. Dr. Papenroth reports in an organic coating paper: "In the aging test, not only the presence of water is the main reason to increase the frequency of the wetting and drying cycles, but also to refute all other conditions, which can accelerate the aging process." Although there are some differences in the relationship between the effective relative humidity of the sample surface and the relative humidity of the sample chamber, humidity is an important factor, which is consistent.

2, temperature control The simplest method of accelerating the aging reaction is heating, but care must be taken to adjust the temperature not to exceed the temperature point that leads to different test results. Crude oil refining is an example. It is heated during the distillation process. When the heating is carefully adjusted, the crude oil can be decomposed into its various components, but adding too much heat will cause a catastrophe.
Similarly, in an accelerated aging procedure, testing at the wrong temperature will cause irregular experimental results. So it's important to know what the final product temperature is in order to program them into an accelerated test cycle.
Traditionally, a test temperature has been measured using a blackboard thermometer. In theory, the blackboard temperature represents the maximum sample temperature. Although there are some differences in the structure of the sensor, the extreme importance of temperature control is unanimously recognized.
In the United States, virtually all ageing test specifications use the blackboard temperature as specified by the ASTM recommendations for G26 and G23. One exception is ASTMG53, where a fluorescent device is used, using a thermometer of a different geometry.
In Germany, a different thermometer for the plastics industry has been developed by their standard organization DIN. They believe that sensors mounted on metal plates do not accurately represent the temperature at which plastics are exposed, so it is recommended to use a sensor mounted on a plastic object. . This thermometer can also be used in the Jerry UV series of instruments.
The sensor is mounted on an exposure rack attached to the sample and reaches the electronic system through an acquisition system to continuously control and monitor the temperature.

3, bright / dark cycle alternate light / dark cycle is an important part of most aging test cycle, has been proved to be meaningful for automotive interior equipment, accessories product testing. In dark cycles, the instrument can be programmed to resemble a high humidity condition in a car at night or combined with water spray on the back of the product to create condensation on the paint panel.
Some instruments rotate the sample so that the sample rotates against the light source, alternately facing the light or facing away. This makes the sample exposed to a light/dark state, and it does not expose the sample to different humidity and temperature conditions. The same environmental conditions remain when the sample is facing the light, except that the sample is not irradiated. In order to have a true light/dark condition, the light source is turned on and off at some predetermined time interval. The instrument must have independent temperature and humidity controls during the light/dark period.

4, air pollution to establish materials in the construction site polluted air exposure to the standard method of aging has done very little. SherwinWilliam has done some basic research on the effects of nitrogen dioxide and sulfur dioxide on paint boards. The material is also exposed to temperature, moisture and daylight simulated with a xenon lamp. AATCC also did a combination of industrial pollution and Xenon arc exposure to evaluate the combined effects of textiles. It is clear that as time goes on, the evaluation of the combination of industrial pollution and sunlight will pay more attention. Therefore, the aging apparatus should also have the ability to use polluting gases such as nitrogen dioxide, sulfur dioxide and ozone.

5. Detection and Control of Radiation When we discuss the light source before, the quality of the known light source is extremely important in designing an accelerated aging test procedure. It must be remembered that most tests are to simulate outdoor natural conditions, so the light source should be as Close to natural daylight. Keep in mind that exposing materials to an environment that is not endured by end use may produce abnormal results.

Our short selection of four sources clearly shows that xenon lamps with borosilicate glass and outer filter sets are the best simulations for natural light. So Jerry Instruments chose to focus its technology on the xenon lamp system.

Changing the quality of the radiant energy reaching the sample can be done by changing the inner and outer filter sets. For example, the borosilicate glass of the outer filter sleeve would be soda lime glass, which would change the radiation like unfiltered daylight into filtered daylight. Replacing the inner glass sleeve with quartz and retaining the borosilicate glass as the outer glass sleeve will slightly increase the short-wave (UVB) energy without sacrificing the spectral distribution. The inner and outer glass sleeves are all quartz, and the UV radiation generated can be as low as 180 nm, so the xenon lamp system is very flexible.

We have discussed the quality of light, the importance of quantity, and naturally it raises the question: How can we control these two important factors? We have said that changing the filter sleeve used in xenon lamps can change the quality of light, that is, SPD can change the effect of aging glass in sunlight, and how to ensure that samples are exposed to the same energy level throughout the test.

Experiments have shown that under a fixed voltage wattage, the xenon lamp that has been used for 120 hours has much more radiation than the xenon lamp that has been used for 1500 hours. That is, if the total exposure time of a sample is 1500 hours, then in the first few hundred hours, the sample will receive more sunlight than when it is used. But if we introduce an automatic radiation control system, the sample receives the same energy both in the new and old lamps. Controlling the output of the light source is not only necessary, but is also necessary for research and development of aging tests.

In order to achieve constant radiation, Jerry Instruments' JR-SUN/CI (ConstantIrradiance) series of instruments are equipped with narrow-band light monitors. The radiant energy of the system receiving the xenon lamp is transmitted through a quartz light bar to a test box outside the test chamber. In the test box, first through a narrow-band filter (340nm or 420nm) and then irradiated onto the photodetector, converted into an electrical signal, the signal is sent to the detection circuit to compare with the set value, if the measured value is less than the set value, That is, the radiation is below the required level, and the power regulator receives the control signal to increase the power of the lamp so that the radiation reaches the set point. If the radiation is above the required level, the system will automatically reduce the power until the radiation reaches the set point.

In addition to automatically controlling the radiant energy constant, the light monitor integrates the radiant power over time to determine how much radiant energy the sample has received. The predetermined total radiation energy can be programmed by using a resettable countdown counter. During the experiment, the integration circuit will drive the counter to accumulate in 0.1 kJ increments, causing the counter to gradually decrease from the set point to zero. When the zero point is reached, the instrument automatically turns off. The end of this exposure is determined by the cumulative total energy received by the sample, not by the clock.

The flexibility of the water-cooled xenon lamp combined with the constant radiation control system makes the Jerry Instrument CI series aging instrument an excellent accelerated aging test tool.

As we mentioned at the outset, natural weather phenomena are complex processes, so care must be taken to choose a system that simulates the process in the laboratory. It should have the ability to control conditions like moisture, temperature, and light/dark cycles. And most importantly, it should provide a light source that simulates the radiant energy that the sample is exposed to under end use conditions. The instrument can further repeat the exposure conditions, so that the aging evaluation done last year can be compared with the aging evaluation done today.

Here we focus on accelerating the requirements and functions of climate aging test instruments, but keep in mind that tests in weathering or fading aging testers may not be, and probably should not be, the only way to evaluate the performance of a material. This evaluation is of course a very important part, but other factors like freezing and salt spray also need to be considered. For example, an aging test for evaluating paint on an oil well platform can be carried out in turn in an aging apparatus, a freezer compartment, and a salt spray test. Jereh equipment has also selected an extreme weathering tester where the test temperature can be as low as minus 40 degrees.

Finally, remember that the most important factor in choosing an accelerated aging instrument is the knowledge of the product you are evaluating. This is the general basis for designing the laboratory's accelerated aging test procedures to achieve the best correlation between the results achieved and the actual conditions of use.

Shenzhen Jerry Test Equipment Co., Ltd. Main Products:

1. Environmental test chamber: temperature and humidity test chamber, programmable temperature and humidity test chamber,

High and low temperature alternating heat and humidity test chamber, high and low temperature chamber, high temperature oven, electric blast drying oven, thermal shock test chamber, sand dust test box, rain test chamber, xenon lamp weatherproof test box, ultraviolet weather resistant test box, Vibration test bench, drop test bench, aging room, salt spray corrosion test box, mobile phone notebook testing equipment and other products, and dedication to develop special test equipment for the majority of users.

Second, mobile phone reliability testing equipment, we provide customers with good technology, such as professional technology, exquisite processing technology, meticulous assembly and detailed quality inspection: such as horizontal plug life test machine, mobile phone drum drop test machine, mobile phone Vibration wear tester, button life tester, alcohol rubber wear tester, plug force tester, terminal plug life tester, ESD electrostatic discharge generator, pencil hardness tester, tape friction life tester, mobile phone anti-cell Twist test machine, mobile phone micro drop test machine, mobile phone directional drop test machine, mobile phone free fall test machine, falling ball impact test machine and other communication mechanics testing equipment.