Optimization of Adhesion Strength and Microstructure Properties by Using Response Surface Methodology in Enhancing the Rice Husk Ash-Based Geopolymer Composite Coating.

Mohd Salahuddin Mohd Basri,Faizal Mustapha,Mohd Ridzwan Ishak,Norkhairunnisa Mazlan

doi:10.3390/polym12112709

Mohd Salahuddin Mohd Basri, Faizal Mustapha + Show 2 more

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https://doi.org/10.3390/polym12112709

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Journal: Polymers	Publication Date: Nov 16, 2020
Citations: 15	License type: CC BY 4.0

Affiliation: Universiti Putra Malaysia

Abstract

As a result of their significant importance and applications in vast areas, including oil and gas, building construction, offshore structures, ships, and bridges, coating materials are regularly exposed to harsh environments which leads to coating delamination. Therefore, optimum interfacial bonding between coating and substrate, and the reason behind excellent adhesion strength is of utmost importance. However, the majority of studies on polymer coatings have used a one-factor-at-a-time (OFAT) approach. The main objective of this study was to implement statistical analysis in optimizing the factors to provide the optimum adhesion strength and to study the microstructure of a rice husk ash (RHA)-based geopolymer composite coating (GCC). Response surface methodology was used to design experiments and perform analyses. RHA/alkali activated (AA) ratio and curing temperature were chosen as factors. Adhesion tests were carried out using an Elcometer and a scanning electron microscope was used to observe the microstructure. Results showed that an optimum adhesion strength of 4.7 MPa could be achieved with the combination of RHA/AA ratio of 0.25 and curing temperature at 75 °C. The microstructure analysis revealed that coating with high adhesion strength had good interfacial bonding with the substrate. This coating had good wetting ability in which the coating penetrated the valleys of the profiles, thus wetting the entire substrate surface. A large portion of dense gel matrix also contributed to the high adhesion strength. Conversely, a large quantity of unreacted or partially reacted particles may result in low adhesion strength.

Highlights

In many applications, such as oil and gas, building construction, offshore structures, ships and bridges, steel is widely used as the main component
Response surface methodology (RSM) proved to be an adequate tool to study the relationship between factors which significantly influenced adhesion properties
From the analysis and investigation, adhesion strength of geopolymer composite coating (GCC) was highly significantly influenced by all factors and their interactions (p < 0.000) except for rice husk ash (RHA)/AA ratio which was very significant at p < 0.004

Summary

Introduction

In many applications, such as oil and gas, building construction, offshore structures, ships and bridges, steel is widely used as the main component. In order to provide effective protection against corrosion and improve the biological performance of the substrate, surface coating. The performance and reliability of coatings rely on the adhesion between the coating and the substrate surface. Expansion and contraction during temperature changes need to be considered in order for the coating material to perform over an extended period of time. The coating material itself must be durable and have good interfacial bonding between coating and substrate. Without excellent adhesion strength between coating and substrate, the component underneath the coating will be exposed to harsh environments such as corrosive fluids, flame and heat, and abrasive particles when the coating delaminates or breaks off into small flakes or pieces

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