PSI - Issue 10

I. Iliopoulos et al. / Procedia Structural Integrity 10 (2018) 295–302

298

I. Iliopoulos et al. / Structural Integrity Procedia 00 (2018) 000 – 000

4

i

EM



(2)

( R mpy corr

) 0.13

  corr

d

2.5. Condensation phenomena investigation The construction of a lab-scale plexiglas chamber (box) with 15x15x17 cm dimensions was necessary for the assessment of droplet condensation on the samples of interest. The chamber was designed with controllable moisture and temperature capabilities through an Arduino automation board and sample and chamber temperature was continuously controlled and recorded. A Peltier thermoelectric cooling element was used in order to achieve sub ambient temperature on the sample and humidity was produced through a commercial DC 24V 35×28 mm Ultrasonic Atomizer Air Humidifier (Fig.1d & e). Condensation phenomena were observed for 100% RH @ 20 o C and @ 40 o C at 5, 7 and 10 o C sample’s temperature. Water collection rates were calculated out of mean values out of 3 measurements. Through the CRESCENDO MODEL 175 spraying gun suitable samples were air sprayed showing smooth surfaces and no physical observed defects (Fig.1). For each sample the coating thickness and mass were calculated through Vernier caliper (5-points average) and a 5-digit analytical weight (mass difference before and after the top coating) respectively. All samples were proper adhered according to ISO 2409 tests. After subjecting the samples to 40% H 2 SO 4 , 40% HNO 3 , 40% HCl environments at RT and at 60 o C, gravimetric mass loss per surface was recorded. Results are depicted in Fig.2 for 40% H 2 SO 4 , 40%HNO 3 and 40% HCl respectively. 3. Results and discussion

0 24 48 72 96 120 144 168 192 -8.0 -7.5 -7.0 -6.5 -6.0 -5.5 -5.0 -4.5 -4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 Blank PU Acrylic Epoxy Mass Loss/surface [%] b) @40% HNO 3 , 20 o C

-8 -6 -4 -2 0

-0.50 -0.45 -0.40 -0.35 -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00

c)

a)

0 24 48 72 96 120 144 168 192 -24 -22 -20 -18 -16 -14 -12 -10 Blank PU Acrylic Epoxy Mass Loss/surface [%] @40% HCl, 20 o C

Blank PU

Acrylic Epoxy Mass Loss/surface [%]

@40% H 2 SO 4 , 20 o C

0 24 48 72 96 120 144 168 192

Time [h]

Time [h]

Time [h]

-9 -8 -7 -6 -5 -4 -3 -2 -1 0

0 24 48 72 96 120 144 168 192 -5.0 -4.5 -4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 Blank PU Acrylic EPOXY Mass Loss/surface [%] Time [h] @40% H 2 SO 4 , 60 o C d)

0

f)

-5

e)

-10

-15

0 24 48 72 96 120 144 168 192 -16 -15 -14 -13 -12 -11 -10 Blank PU Acrylic Epoxy @40% HNO 3 , 60 o C

-20

Blank PU

-25 Acrylic Epoxy Mass Loss/surface [%]

Mass Loss/surface [%]

@40% HCl, 60 o C

0 24 48 72 96 120 144 168 192 -30

Time [h]

Time [h]

Fig. 2. Mass loss at 20 o C (top row) and 60 o C (lower row) in 40% H

2 SO 4 (a), (d), 40% HNO 3 (b), (e) and 40% HCl (c), (f).

According to Fig.2, PU and Epoxy coatings are found to be significantly tolerant under 40% H 2 SO 4 for both experimental temperatures. Slightly enhanced anticorrosive capabilities, in comparison with blank samples also was