ASTM D7869

ASTM D7869是針對交通工具用涂料的氙燈老化測試標準：

ASTM D7869指定控制輻照度，Q-SUN氙弧燈和用水器具的操作程序。  新標準規定了使用可控輻照度氙弧燈和噴水裝置的光照老化試驗程序。在此程序中使用一個或多個燈管和濾光片產生的輻照度類似于自然界中太陽光的紫外線和可見光部分。同時模擬了汽車外部涂層在自然氣候條件下的吸水性和應力循環。本標準同時適用于其他交通工具的外部涂層，例如：航空器、卡車和軌道車輛。

ASTM D7869-13新標準規定的氙弧燈輻照度在 0.4-0.8 W/m2@340nm 之間，在幾個黑暗試驗階段向樣品噴水，在實驗過程中涂層會吸收和釋放水份。干/濕和冷/熱循環會使材料的機械應力產生變化。這些測試條件模擬亞熱帶氣候（例如南佛羅里達）條件下涂層材料的物理和化學應力

詳細的試驗程序如下：

ASTM D7869英文簡介

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