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濕熱試驗(yàn)

2016-05-31 09:28:31

濕熱試驗(yàn)與鹽霧試驗(yàn)的主要區(qū)別是濕熱試驗(yàn)的霧滴沒(méi)有鹽分是蒸餾水，雖然鹽滴因其導(dǎo)電率高、叉含氯離子而腐蝕作用劇烈，但對(duì)滲透壓而言，蒸餾水的活度高，涂層是半透膜，蒸餾水滲入漆膜的能力比鹽液強(qiáng)。水分透入漆膜，在兩層漆膜之間積聚，會(huì)降低層間附著力，而起泡。隨后再向深入一步發(fā)展，到達(dá)漆膜與底板之間，降低附著力，導(dǎo)致漆膜起泡，同時(shí)水分與金屬底板接觸，產(chǎn)生電化學(xué)腐蝕作用。在漆膜內(nèi)吸收水分，會(huì)引起漆膜膨脹而產(chǎn)生內(nèi)應(yīng)力，降低附著力而起泡，漆膜吸水率在蒸餾水中比鹽水中高，就對(duì)涂膜的破壞力來(lái)說(shuō)，濕熱試驗(yàn)是很苛刻的。

總體概況

濕熱試驗(yàn)是將涂有漆膜的樣板或?qū)嵨镏糜跍囟群蜐穸仁芸刂频拿荛]試驗(yàn)箱內(nèi)，一定時(shí)間后觀察起泡、腐蝕及附著力下降等變化，評(píng)定涂膜抵抗?jié)駸崴?有時(shí)包含有凝露)能力的試驗(yàn)。考核涂層對(duì)濕熱帶氣候的環(huán)境適應(yīng)性和耐蝕能力。濕熱試驗(yàn)時(shí)，涂層的耐水性和水汽滲透性比一般常溫浸水試驗(yàn)失效要快。濕熱試驗(yàn)引起的腐蝕不及鹽霧試驗(yàn)劇烈。

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涂層耐濕熱性能檢測(cè)相關(guān)技術(shù)標(biāo)準(zhǔn)

標(biāo)準(zhǔn)名稱：Standard Practice for Testing Water Resistance of Coatings in 100% Relative Humidity
標(biāo)準(zhǔn)編號(hào)：ASTM D2247 - 11
標(biāo)準(zhǔn)概述：Water can cause the degradation of coatings, so knowledge of how a coating resists water is helpful for assessing how it will perform in actual service. Failure in tests at 100 % relative humidity may be caused by a number of factors including a deficiency in the coating itself, contamination of the substrate, or inadequate surface preparation. This practice is therefore useful for evaluating coatings alone or complete coating systems.Tests at 100 % relative humidity are used for specification acceptance, quality control, and research and development for coatings and substrate treatments. Some tests are used for a pass or fail determination at an arbitrary time. A coating system is considered to pass if there is no evidence of water-related failure after a period of time. Other tests are used to monitor degree of failure as a function of exposure time.

標(biāo)準(zhǔn)名稱：漆膜耐濕熱測(cè)定法
標(biāo)準(zhǔn)編號(hào)：GB/T 1740-2007
發(fā)布日期：2007-09-11
實(shí)施日期：2008-04-01
標(biāo)準(zhǔn)概述：本標(biāo)準(zhǔn)規(guī)定了色漆、清漆或相關(guān)產(chǎn)品的涂層抗高溫、高濕環(huán)境能力的試驗(yàn)方法。本標(biāo)準(zhǔn)適用于漆膜耐濕熱性能的測(cè)定。

標(biāo)準(zhǔn)名稱：Standard Practice for Testing Water Resistance of Coatings Using Water Fog Apparatus
標(biāo)準(zhǔn)編號(hào)：ASTM D1735 - 08
標(biāo)準(zhǔn)概述：This practice covers the basic principles and operating procedures for testing water resistance of coatings in an apparatus similar to that used for salt spray testing.This practice is limited to the methods of obtaining, measuring, and controlling the conditions and procedures of water fog tests. It does not specify specimen preparation, specific test conditions, or evaluation of results.