Abrasion tests, coatings

Resistance to abrasion The resistance to abrasion of electroless nickel-phosphorus hardened to 600 Hy, assessed by Taber abrasion tests, has been found to be double that of electroplated nickel However, electroless nickel coatings are not suitable for applications where two electroless nickel surfaces rub together without lubrication unless the values of hardness are made to differ by over 200 Hy units. Galling of aluminium, titanium or stainless steel may be overcome by applying electroless nickel to one of the two mating surfaces. 

Abrasion tests In these tests the end point is normally taken as the amount of abrasion required to penetrate the coating. The results thus reflect the strength of the coating, its cohesion, and in some cases its adhesion to the basis metal as well as resistance to abrasion. 

ANOVA for percent of fibers remaining coated after the abrasion test... 

Effect of the line speed and concentration, independent of the coupling agent, on percent of fibers remaining coated after the abrasion test... 

Haluska, L. A. Wear Testing of Abrasion - Resistant Coated Plastics, Special Technical Publication 769, American Society for Testing and Material, (1982). 

The results of an abrasion test (ASTM D4060-01) carried out for 500 test cycles are presented in Table 11.4. Wear index decreased monotonically with the increase in the HDDA content in the coating formulation, which showed that the abrasion resistance property of BDGDA improved in the presence of HDDA. Improvement in abrasion resistance of the coating with increase in HDDA content is attributed to the increase in the cross-link density on addition of HDDA. 

Figure 5.2. Example of a zero-order measurement of combinatorial materials Abrasion resistance of coatings from measurements of scattered light from each organic coating in a 48-element array at a single wavelength upon abrasion test. (A) Reflected-light image of the coatings array (B) representative data from a single material in the array.

Jet-abrasion test n. A test for the abrasion resistance of coatings in which the time required for an air blast of fine abrasive particles to wear through the coating is measured (ASTM D 658, Section 06.01). 

Geng and He [52], apart from the pencil test described in Section 9.2.4 used additionally a sand impact setup to test their coatings. In the sand abrasion test, 40 g sand grains with diameters of 100-300 pm were used to impact the coating surface from a height of 30 cm in 1 min. Subsequently, the coating was cleaned with water. The water and ethylene glycol APCAs before and after sand abrasion test showed approximately the same values. 

The superomniphobic polyester fabrics tested with the blade test by the same group (Zhou et al.) were also tested under laimdry and circular abrasion [49]. In the machine laundry process, the coated fabric did not show changes in the APCAs of water, hexadecane or ethanol after 200 cycles of washing. However, the SA values increased to 4.5°, 36.7°, and 47.5° for water, hexadecane, and ethanol respectively. After 20000 abrasion cycles nearly no nanoparticles could be observed on the top surface. However, the damaged surface after the abrasion test was healable when the coated fabric was heated at 140° C for 30 min. The APCAs of water and hexadecane recovered to 171° and 152°, respectively. However, the heat treatment could increase the APCA of ethanol only to 127°. 

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