Self-lubricating polymer composite coatings, with tailorable tribological and mechanical properties, have been widely employed on mechanical parts to reduce friction and wear, which saves energy and improves the overall performance for applications such as aerospace satellite parts, shafts, gears, and bushings. The addition of functional fillers can overcome the limitations of single-polymer coatings and extend the service life of the coatings by providing a combination of low friction, high wear resistance, high load bearing, high temperature resistance, and high adhesion. This paper compares the heat resistance, and the tribological and mechanical properties of common polymer matrices, as well as the categories of functional fillers that improve the coating performance. Applicable scopes, process parameters, advantages, and limitations of the preparation methods of polymer coatings are discussed in detail. The tribological properties of the composite coatings with different matrices and fillers are compared, and the lubrication mechanisms are analyzed. Fillers reduce friction by promoting the formation of transfer films or liquid shear films. Improvement of the mechanical properties of the composite coatings with fillers of different morphologies is described in terms of strengthening and toughening mechanisms, including a stress transfer mechanism, shear yielding, crack bridging, and interfacial debonding. The test and enhancement methods for the adhesion properties between the coating and substrate are discussed. The coating adhesion can be enhanced through mechanical treatment, chemical treatment, and energy treatment of the substrate. Finally, we propose the design strategies for high-performance polymer composite coating systems adapted to specific operating conditions, and the limitations of current polymer composite coating research are identified.

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A review on tribology of polymer composite coatings

The chemical and microstructural analysis of the adhesive properties of epoxy resin coatings modified using waste glass powder

Lightweight concrete from a perspective of sustainable reuse of waste byproducts

Non-destructive testing (NDT) and semi-destructive testing (SDT) have recently been more frequently used for the evaluation and condition assessment of concrete floors in various types of buildings. The subject of the article is to briefly introduce the reader to the problem of adhesion between overlays and substrates in concrete floors and to illustrate the current state of knowledge on the subject. The aim of this paper was to briefly describe the recently used non-destructive and semi-destructive testing methods and the parameters useful for characterizing the adhesion between overlays and substrates in concrete floors, as well as the methods useful to characterize the functional properties of the overlays. A recent literature survey, related to the adhesion between the overlays and substrates in concrete floors, is thus shown. Special emphasis was placed on the critical review of the current research results. Based on the analysis of the literature review, research gaps have been presented in order to highlight future research directions.

https://www.mdpi.com/2075-5309/9/9/203/pdf

Evaluation of the Adhesion between Overlays and Substrates in Concrete Floors: Literature Survey, Recent Non-Destructive and Semi-Destructive Testing Methods, and Research Gaps

The partial replacement of cement in concrete with the addition of granite powder and fly ash can help to reduce the carbon dioxide (CO2) emissions into the atmosphere associated with cement production. The aim of the article is to compare the performance of granite powder and fly ash for the sustainable production of air-cured cementitious mortars. The morphological, chemical, and granulometric properties of these additives were first compared with the properties of cement. Afterward, a series of mortars modified with the addition of granite powder and fly ash was made. The properties of the fresh mixes and the mechanical properties of the hardened composites were then tested. Finally, based on the obtained results, a cost analysis of the profitability of modifying cementitious composites with granite powder or fly ash was investigated. The obtained results allow similarities and differences between granite powder and fly ash in relation to cement to be shown. To conclude, it should be stated that both of these materials can successfully be used for the sustainable production of air-cured cementitious composites. This conclusion has a significant impact on the possibility of improving the natural environment by reducing the amount of cement production. More sustainable production of cement-based materials could enable CO2 emissions to be decreased. The use of granite powder for the production of cementitious mortars can significantly reduce the amount of this material deposited in landfills.

Granite Powder vs. Fly Ash for the Sustainable Production of Air-Cured Cementitious Mortars.

Potential use of granite waste sourced from rock processing for the application as coarse aggregate in high-performance self-compacting concrete

This paper describes a study conducted to evaluate the effect of texturing of the surface of concrete substrate on the pull-off strength (fb) of epoxy resin coating. The paper investigates a total of seventeen types of textures: after grooving, imprinting, patch grabbing and brushing. The texture of the surface of the concrete substrate was prepared during the first 15 min after pouring fresh concrete into molds. The epoxy resin coating was laid after 28 days on hardened concrete substrates. To investigate the pull-off strength of the epoxy resin coating to the concrete substrate, the pull-off method was used. The results were compared with the results obtained for a sample prepared by grinding, normative minimal pull-off strength values and the values declared by the manufacturer. During this study twelve out of fifteen tested samples achieved a pull-off strength higher than 1.50 MPa. It was found that one of the imprinting texturing methods was especially beneficial.

https://www.mdpi.com/2079-6412/9/2/143/pdf

The Effect of Texturing of the Surface of Concrete Substrate on the Pull-Off Strength of Epoxy Resin Coating

Nowadays, the recycled fine aggregate sourced from construction and demolition waste is not frequently used in manufacturing of epoxy resin coatings. Therefore, the main novelty of the article is to prepare green epoxy resin coatings modified with recycled fine aggregate in a replacement ratio of natural fine aggregate ranged from 20 to 100%. The microstructural properties of the aggregates and epoxy resin were analyzed using micro-computed tomography, scanning electron microscopy and nanoindentation. The macroscopic mechanical properties were examined using pull-off strength tests. The highest improvement of the mechanical properties was observed for epoxy resin coatings modified with 20% of natural fine aggregate and 80% of recycled fine aggregate. It has been found that even 100% of natural fine aggregate can be successfully replaced using the recycled fine aggregate with consequent improvement of the pull-off strength of analyzed epoxy resin coatings. In order to confirm the assumptions resulting from the conducted research, an original analytical and numerical failure model proved the superior behavior of modified coating was developed.

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Engineering and Manufacturing Technology of Green Epoxy Resin Coatings Modified with Recycled Fine Aggregates

This paper presents an experimental study on the assessment of the cement-based materials properties made with marble powder (MP) at different replacement ratios (0%, 5%, 10%, and 15%) of cement by using the ultrasonic pulse velocity (UPV) test. The used MP has a Blaine fineness similar to that of Portland cement. The physical and the chemical characteristics of Portland cement and MP were determined. To determine the UPV values, cubic specimens (50 × 50 × 50 mm3) of cement paste and mortar were prepared and cured either in air at a temperature equal to 22 ± 2 °C and relative humidity equal to 20 ± 1%, or in water at a temperature equal to 20 ± 1 °C. The experimental tests including the UPV, the compressive strength (fcd), and the apparent density (ϒad) were conducted at 3, 7, 28, and 65 days, the relationship between each of these parameters were presented. Additionally, economic performance of cement and waste MP used in this study was performed. The results show that the use of MP as partial replacement of cement causes a decrease in the compressive strength and apparent density in both curing conditions. In addition, the results show a good relationship between the destructive test and non-destructive test adopted by UPV.

https://www.mdpi.com/2075-5309/10/3/38/pdf

Ultrasonic Evaluation of Cement-Based Building Materials Modified Using Marble Powder Sourced from Industrial Wastes

This article presents studies that were performed in order to improve the subsurface properties of horizontally-formed cementitious composites using tin(II) fluoride nanoparticles. The main aim of the study was to solve the problem of the decrease in subsurface properties caused by mortar bleeding and the segregation of the aggregate along the height of the overlay. The article also aims to highlight the patch grabbing difficulties that occur during the process of forming horizontally-formed cementitious composites. Four specimens were analyzed: one reference sample and three samples modified with the addition of 0.5, 1.0, and 1.5% of tin(II) fluoride nanoparticles in relation to the cement mass. To analyze the mechanical properties of the specimens, non-destructive (ultrasonic pulse velocity) and destructive tests (flexural tensile strength, compressive strength, abrasion resistance, pull-off strength) were performed. It was indicated that due to the addition of the tin(II) fluoride, it was possible to enhance the subsurface tensile strength and abrasion resistance of the tested cementitious composites. To confirm the obtained macroscopic results, the porosity of the subsurface was measured using SEM. It was also shown that the addition of the tin(II) fluoride nanoparticles did not reduce its flexural and compressive strength. The results show that horizontally-formed cementitious composites with the addition of 1.0% of tin(II) fluoride nanoparticles in relation to the cement mass obtained the most effective mechanical performance, especially with regard to subsurface properties.

https://www.mdpi.com/2079-6412/10/1/83/pdf

Kamil Krzywiński

Papers

Potential use of granite waste sourced from rock processing for the application as coarse aggregate in high-performance self-compacting concrete

The Effect of Texturing of the Surface of Concrete Substrate on the Pull-Off Strength of Epoxy Resin Coating

Engineering and Manufacturing Technology of Green Epoxy Resin Coatings Modified with Recycled Fine Aggregates

Ultrasonic Evaluation of Cement-Based Building Materials Modified Using Marble Powder Sourced from Industrial Wastes

Attempts to Improve the Subsurface Properties of Horizontally-Formed Cementitious Composites Using Tin(II) Fluoride Nanoparticles