ASTM D7869测试标准

ASTM D7869是针对交通工具用涂料的氙灯老化测试标准：

ASTM D7869指定控制辐照度，Q-SUN氙弧灯和用水器具的操作程序。  新标准规定了使用可控辐照度氙弧灯和喷水装置的光照老化试验程序。在此程序中使用一个或多个灯管和滤光片产生的辐照度类似于自然界中太阳光的紫外线和可见光部分。同时模拟了汽车外部涂层在自然气候条件下的吸水性和应力循环。本标准同时适用于其他交通工具的外部涂层，例如：航空器、卡车和轨道车辆。

ASTM D7869-13新标准规定的氙弧灯辐照度在 0.4-0.8 W/m2@340nm 之间，在几个黑暗试验阶段向样品喷水，在实验过程中涂层会吸收和释放水份。干/湿和冷/热循环会使材料的机械应力产生变化。这些测试条件模拟亚热带气候（例如南佛罗里达）条件下涂层材料的物理和化学应力

详细的试验程序如下：

ASTM D7869英文简介

Significance and Use

5.1 This test procedure is used to simulate the physical and environmental stresses that a coating for exterior transportation applications (for example, automotive) is exposed to in a subtropical climate, such as southern Florida. It has been found that such a subtropical climate causes particularly severe deterioration of such coatings. The long water exposures and wet/dry cycling found in southern Florida are particularly important for this deterioration, in addition to the high dosage of solar radiation (3). This practice was developed to address the deficiencies of historical tests used for transportation coatings, especially automotive coatings (4).

Note 1—This test procedure was developed through eight years of cooperative testing between automotive and aerospace OEM’s, material suppliers, and test equipment manufacturers. See References for published papers on this research.

1. Scope

1.1 This practice specifies the operating procedures for a controlled irradiance xenon arc light and water apparatus. The procedure uses one or more lamp(s) and optical filter(s) to produce irradiance similar to sunlight in the UV and visible range. It also simulates the water absorption and stress cycles experienced by automotive exterior coatings under natural weathering conditions. This practice has also been found applicable to coatings on other transportation vehicles, such as aircraft, trucks and rail cars.

1.2 This practice uses a xenon arc light source with specified optical filter(s). The spectral power distribution (SPD) for the lamp and special daylight filter(s) is as specified in Annex A1. The irradiance level used in this practice varies between 0.40 and 0.80 W/(m2·nm) at 340 nm. Water is sprayed on the specimens during portions of several dark steps. The application of water is such that the coatings will absorb and desorb substantial amounts of water during testing. In addition, the cycling between wet/dry and warm/cool will induce mechanical stresses into the materials. These test conditions are designed to simulate the physical and chemical stresses from environments in a subtropical climate, such as southern Florida.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents

ASTM Standards

D4517 Test Method for Low-Level Total Silica in High-Purity Water by Flameless Atomic Absorption Spectroscopy

G113 Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials

G147 Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests

G151 Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources

G155 Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials