Sialon and Alumina Modified UV-Curable Coatings with Improved Mechanical Properties and Hydrophobicity

This article describes the modification of UV-curable coatings with silicon aluminum oxynitride (Sialon) and aluminum oxide (Alu C), which improve the hydrophobicity of the coating surface and the scratch hardness. The contact angle is greater due to surface roughness being enhanced with inorganic fillers. Improved scratch resistance results from the formation of a sliding layer triggered by the diffusion of Sialon or alumina on the coating surface. One can observed an increase in the surface hydrophobicity as well as in the scratch hardness (up to 100%) when small amounts (5 wt.%) of the inorganic compounds are added. Imaging microscopies, i.e., SEM, OM, and AFM (with nanoscopic Young’s modulus determination), revealed the good distribution of both types of fillers in the studied matrix.

Canola Oil based Poly (Ester–Ether–Amide–Urethane) Nanocomposite and Its Anti-Corrosive Coatings

The environmental and health hazards associated with petro-based chemicals have motivated the researchers to replace them partially or wholly with renewable resource-based polymers. Vegetable oils serve as an excellent alternative to this end as they are cost effective, eco-friendly, easily available and rich with functional groups amenable to chemical reactions. The aim of the research work is to prepare Canola oil [CANO] derived poly (ester–ether–amide–urethane) (CPEEUA) nanocomposite coating material using N,N-bis (2-hydroxyethyl) fatty amide [CFA] obtained from CANO, Lactic acid [LA], and reinforced with Fumed Silica [FS]. CPEEUA was obtained by esterification, etherification, and urethanation reactions and its structure was confirmed from FTIR and NMR spectral analyses. CPEEUA/FS coatings were found to be scratch resistant, flexible, well-adhered to mild steel panels, and hydrophobic with 2.0–2.5kg scratch hardness, 150lb/inch impact resistance and >90° contact angle value. They exhibited good corrosion protection in 3.5 wt% NaCl solution as investigated by Potentiodynamic Polarization and Electrochemical Impedance tests. CPEEUA coatings are safe for usage up to 200 °C.

Analysis of the Statistical Comparability of the Hardness and Wear of Polymeric Materials for Orthodontic Applications

Background: Clinical success depends on the contact strength and wear resistance of medical devices made of polymer materials. The scientific goal resulted from the problem of using different methods of surface evaluation of materials used in the production of orthodontic appliances. The purpose of the work was an experimental comparative assessment of indentation hardness and scratch hardness and the sliding wear of four selected polymeric materials used in the manufacture of orthodontic appliances. Methods: Four commercial materials were compared. Shore hardness tests and a scratch test with a Rockwell indenter were performed. A sliding wear test was performed using the ball-on-disc method. Statistical PCA and correlation analyses were performed. Results: The results of scratch hardness measurements using a contact profilometer correlated with the Shore hardness to a greater extent than measurements made using an optical microscope. PCA showed that Shore hardness explains 45% of the total variance in all the results across the materials. Conclusions: The scratch hardness method allows for a more explicit ranking of orthodontic polymeric materials when measurements are made with a profilometer. The ranking of sliding wear resistance should be made separately.

Characterization of Surface Coating Techniques for Improved Performance

Surface coating has evolved with time, tracking the demands of the processing industry. This research activity, studies the significance of powder coatings in the evolution of existing conventional surface coating technology for their practical applications in the field of metal coating, particularly office and home appliances. The first objective of this work involves a systematic comparison between polymer powder coatings with liquid-based coatings. In the second objective, a comparison between the polymer coatings with additive filled powder coating was performed. Various conventional substrates (such as copper, aluminium, galvanized iron, brass, cement plank, wood block) were used for this study. The materials were first dry scuffed and then dipped in 3 in 1 chemical (zinc phosphate chemical and magnesium phosphate) for the primer coat. The prepared substrates were surface coated with liquid paint (on one side of the panel) using spray gun and powder paint (on another side of panel) using electrostatic spraying. The coated panels are then subjected to various standard (ISO) characterization techniques such as Scratch hardness test, Flexibility test, Thickness test, Adhesion test, Impact resistance test etc to analyze the effectiveness of the coatings applied. The quantitative and qualitative results thus obtained using powder coatings were promising (e.g: As the load progressively kept increasing i.e. 1000-2000 gm, mild scratches were noticeable on liquid coated substrates whereas powder coated metal panels have shown a greater resistance to scratch damage) as the test values determined high strength quality and durability (in-line with the standards) in comparison with liquid coatings. Also, the doping of additive (graphene) in small quantity has improved characteristics and qualities of the powder coated materials (e.g: graphene based powder coating has endured scratch hardness test beyond 2500 gms load force compared to simple powder coating). The findings of the current research study has confirmed the advantage of the powder coating technology and also deliberated the effect of fine powder flow ability. The important future prospects of this research work is that., powder coatings will stand on the threshold of exciting breakthroughs thus opening new frontiers by being able to coat thick steel components and even non-metal substrates. Also, the recent advances in powder coating technology with anticorrosive additives will result in bonded metallic coatings that deliver a unique, quality appearance.

MECHANICAL AND TRIBOLOGICAL ANALYSIS OF MONOLITH AND COATING POLYETHERETHERKETONE

In this work, a comparative analysis of the micromechanical and tribological properties of polyetheretherketone (PEEK) in bulk and coating form was performed. The PEEK 708 coating was applied on a Ti6Al4V titanium alloy flat specimen using the electrophoretic deposition method. The micromechanical properties were determined through indentation tests performed using the Vickers method and scratch tests. Based on research work, the Vickers hardness (HV), elastic modulus (E), scratch hardness (HS), and Micro Mar Resistance (MMR) were determined. The tribological properties were defined by the coefficient of friction (fs and fw), which was obtained in scratch tests and ball-on-disk tests. The results of this research indicate, despite the slightly higher Vickers hardness (HV) of the PEEK 708 coating (HV=350 MPa, HS=300 MPa) relative to PEEK bulk (HV=300 MPa, HS=210 MPa), that there is an almost 40% difference between the scratch hardness (HS) values of these PEEK forms. It appears from the result analysis in this paper that testing methods to determine the micromechanical and tribological properties of PEEK in monolith form can be used for both PEEK coatings. Under certain test conditions, the impact of the substrate properties on the results of the PEEK 708 coating was not found.