Degradation Evaluation of Pigmented Long Oil Alkyd Resin Paint Film by Nanoindentation and Scanning Acoustic Microscope

Abstract

The degradation behavior of pigmented long oil alkyd resin (LAR-P) painted on steel in an aqueous 3% NaC1 solution was investigated by nanoindentation and scanning acoustic microscope (SAM) . Young's modulus (E) and hardness (H) , obtained by nanoindentation, of the LAR-P paint film on steel increased at short immersion time and then decreased with increasing immersion time. Furthermore, it wasclarified that the SAM image shows a heterogeneous E distribution. The lower E areas in paint film were observed at short immersion time, while the blisters were observed in the lower E area in the SAM images. The spread of lower E area and blister growth with increasing immersion time, which are difficult to observe by optical method, were clarified by evaluation of the SAM images.

Effect of Film Thickness on Coated Film Degradation by Scanning Acoustic Microscope and Nanoindentation Tester

“…8 The E values of 33 and 47 m films until an immersion time of 600 h diverged in comparison with those of 0 h. The result shows that nonuniform E distribution occurred in NaCl solution and it reflects the E value of a dried specimen. Therefore, the E value affected by time dependence of curing of an alkyd resin and whether the specimen was wet or dry was ignored.…”

“…The E value of an alkyd resin without an immersion test may change with exposing time in air; however, the E value for each film thickness was constant until 500 h. The change of E value against immersion time was affected by pigment and substrate. 8 The E values of 33 and 47 m films until an immersion time of 600 h diverged in comparison with those of 0 h. The result shows that nonuniform E distribution occurred in NaCl solution and it reflects the E value of a dried specimen. Therefore, the E value affected by time dependence of curing of an alkyd resin and whether the specimen was wet or dry was ignored.…”

“…The initiation and growth of blister were nondestructively observed by use of a scanning acoustic microscope ͑SAM͒ 6-8 and the change of the E value of paint film as a change in a physical characteristic was independently measured by use of a nanoindentation tester. [8][9][10] Experimental Materials.-Metal substrate.-Cold rolled steel plate ͑JIS G3141, ISO 3574-86, SPCC/SB, Nippon test panel, 70ϫ150ϫ0.80 mm) was used. The chemical composition of the steel was C 0.08 mass %, Si trace, Mn 0.35, P 0.94, S 0.018, and Fe balance.…”

“…In this study the effect of paint film thickness up to 211 m was investigated for the initiation and growth of blisters between the paint film and steel plate interface ͑abbreviation: F/S interface͒ in a corrosive environment. The initiation and growth of blister were nondestructively observed by use of a scanning acoustic microscope ͑SAM͒ [6][7][8] and the change of the E value of paint film as a change in a physical characteristic was independently measured by use of a nanoindentation tester. [8][9][10]…”

“…The initiation and growth of blister were nondestructively observed by use of a scanning acoustic microscope ͑SAM͒ [6][7][8] and the change of the E value of paint film as a change in a physical characteristic was independently measured by use of a nanoindentation tester. [8][9][10]…”