Nano-particles and fibers-modified cementitious composite (NFCC) can greatly overcome the shortcomings of traditional cementitious materials, such as high brittleness and low toughness, and improve the durability of the composite, which in turn increases the service life of the structures. Additionally, the polymer coatings covering the surface of the composite can exert a good physical shielding effect on the external water, ions, and gases, so as to improve the permeability and chloride ion penetration resistance of the composite. In this study, the effect of three types of polymer coatings on the water contact angle, permeability resistance, and chloride ion penetration resistance of the NFCC with varied water–binder ratios were investigated. Three kinds of polymers (chlorinated rubber coating, polyurethane coating, and silane coating) were applied in two types of coatings, including single-layer and double-layer coatings. Three water–binder ratios of 35 wt.%, 40 wt.%, and 45 wt.% were used for the NFCC. The research results revealed that the surface of the NFCC treated with polymer coatings exhibited excellent hydrophobicity. The permeability height and chloride diffusion coefficient of the NFCC coated with different types of polymer coatings were 31–48% and 36–47% lower, respectively, than those of the NFCC without polymer coatings. The durability of the NFCC was further improved when the polymer coatings were applied to the surface in two-layer. Furthermore, it was discovered that increasing the water–binder ratio of the NFCC would lessen the positive impact of polymer coatings on the durability of NFCC.

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Effect of Polymer Coatings on the Permeability and Chloride Ion Penetration Resistances of Nano-Particles and Fibers-Modified Cementitious Composites

Automotive light-weighting has become an important direction for the development of the automotive industry, and the light-weighting materials are inevitable to be joined. Self-piercing riveting (SPR) is a kind of new process to joint various materials. The SPR and SPR-bonded (SPR-A) joints of AA6061 and DP590 sheets were prepared. The mechanical properties of SPR and SPR-A joints after exposure to neutral salt spray environments for different aging times were tested. The results showed that the shear and fatigue properties of the joints gradually reduced with the increase of salt spray time. In addition, the SPR-A joints not only have higher maximum failure loads but also have larger energy absorption values in shear tests when compared with that of the SPR joints under the same salt spray time. The fatigue test results showed that fretting wear between the rivet-foot and the lower sheet is the main failure mechanism of joints. Moreover, the salt spray time has no obvious effect on the fatigue failure modes of the two kinds of joints. 

Mechanical properties and fatigue failure mechanisms of purely self-piercing riveted (SPR) and hybrid (SPR-bonded) joints under salt spray environment

Water-repellent and corrosion resistance properties of epoxy-resin-based slippery liquid-infused porous surface

A multiple synergistic composite coating with ultrahigh anti-corrosion performance under harsh oxygen environment

A durable superhydrophobic polyphenylene sulfide composite coating with high corrosion resistance and good self-cleaning ability

Superhydrophobic coating based on organic/inorganic double component adhesive and functionalized nanoparticles with good durability and anti-corrosion for protection of galvanized steel

Inverted pyramid-texturing of silicon surface has been proven to have great application potential in silicon solar cells. In this paper, we utilized Ag-assisted chemical etching (Ag–ACE) technology combing with polyvinylpyrrolidone (PVP) to fabricate an inverted pyramid textured Si surface. We call it Ag@PVP–ACE. The effect of different experimental parameters on etching results was observed. We show that the microstructure of the Si surface exhibited two states as the concentration of NH4HF2 and PVP concentration changed: polishing and inverted pyramid texturing. Meanwhile, we found inverted pyramids easier to form at the high temperature and low H2O2 concentration of the etching system. Consequently, compared to inverted pyramid structures fabricated by nanostructure rebuilding (NSR) technology and Ag@PVP–ACE, we consider that Ag@PVP–ACE technology could become a viable strategy for fabricating inverted pyramid textured Si wafers in Si solar cells production.

https://www.mdpi.com/2073-4352/11/5/459/pdf

One-Step Fabrication of Inverted Pyramid Textured Silicon Wafers via Silver-Assisted Chemical Etching Combing with Synergism of Polyvinylpyrrolidone (PVP)

Superhydrophobic coatings with excellent water-repellent properties imply a wide range of application areas. However, improvements are needed in terms of stability and complex processing procedures. In the present study, a superhydrophobic coating on Al sheets was prepared by mixing hexadecyltrimethoxysilane (HDTMS)-modified SiO2 nanoparticles and acid-catalyzed silica sols (HD-SiO2/SiO2 Sol) with polydimethylsiloxane (PDMS) binder. The HD-SiO2 nanoparticles and acid-catalyzed silica sol (SiO2 sol) form a binary graded micro-nanostructure, providing excellent superhydrophobicity (Water Contact Angle = 158.5°, Sliding angle = 0°). Superhydrophobic coatings with excellent water-repellent properties have potential for corrosion prevention. However the commonly used organic resins have poor chemical and mechanical properties. In the present study, the results of outdoor exposure for 30 days, immersion in acid and alkaline solutions for 24 h, grit abrasion, and water impact experiments, respectively, showed that the prepared superhydrophobic coating has good wear resistance. The integrated superhydrophobic coating on the Al sheets exhibited good corrosion inhibition with an efficiency (η) of 98.9%, which is much higher than that of the uncoated sheets. The present study provides a promising approach for producing stable superhydrophobic coatings at a low cost, with the potential to supplant conventional organic resin anti-corrosion coatings.

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Kousuo Dong

Papers

Superhydrophobic coating based on organic/inorganic double component adhesive and functionalized nanoparticles with good durability and anti-corrosion for protection of galvanized steel

One-Step Fabrication of Inverted Pyramid Textured Silicon Wafers via Silver-Assisted Chemical Etching Combing with Synergism of Polyvinylpyrrolidone (PVP)

HD-SiO2/SiO2 Sol@PDMS Superhydrophobic Coating with Good Durability and Anti-Corrosion for Protection of Al Sheets