31 documents found, page 1 of 4

Hybrid sol-gel materials doped with AgY and NaY Zeolites

The sol-gel process is a chemical synthesis often considered as a green technology due to mild conditions preparation since is waste-free and the processing temperature is generally low (e.g., close to room temperature). Also, uses compounds that do not introduce impurities into the end material and excludes the washing stage. Compared to other chemical routes, sol-gel method has several advantages in the desig...

Chloride threshold value to initiate reinforcement corrosion in simulated concr...

The influence of steel surface finishing and pH of simulated concrete pore solutions (SCPS) on the chloride threshold value (CTV) was evaluated. Steel samples were analysed, with four different finishes: as received (T), diamond-polished (D), polished (P500) and pre-oxidized (DH). The studies were performed in SCPS with pH values of 11.6 and 13.5, and of different chloride concentrations. The electrochemical be...

Nanoindentação em materiais de construção

Nesta comunicação apresentam-se desenvolvimentos recentes na caracterização mecânica de materiais de construção por técnicas de micro e nanoindentação.

Revestimentos e pré-tratamentos para mitigação da corrosão em armaduras galvani...

A corrosão de armaduras no betão armado, por carbonatação do betão ou ataque por iões cloreto, é uma das principais causas de degradação de estruturas. A propagação da corrosão após o seu início é geralmente rápida, podendo conduzir à deterioração das estruturas, num curto espaço de tempo, sempre associada a elevados custos de reparação. A utilização do aço galvanizado é considerada uma medida alternativa para ...

Hybrid sol-gel coatings: smart and green materials for corrosion mitigation

Corrosion degradation of materials and metallic structures is one of the major issues that give rise to depreciation of assets, causing great financial outlays in their recovery and or prevention. Therefore, the development of active corrosion protection systems for metallic substrates is an issue of prime importance. The promising properties and wide application range of hybrid sol-gel-derived polymers have at...

Nanoindentação em materiais de construção

Nesta comunicação apresentam-se desenvolvimentos recentes na caracterização mecânica de materiais de construção por técnicas de micro e nanoindentação.

Hybrid sol-gel coatings: Smart and green materials for corrosion mitigation

Corrosion degradation of materials and metallic structures is one of the major issues that give rise to depreciation of assets, causing great financial outlays in their recovery and or prevention. Therefore, the development of active corrosion protection systems for metallic substrates is an issue of prime importance. The promising properties and wide application range of hybrid sol‐gel‐derived polymers have at...

Erratum: Ureasilicate hybrid coatings for corrosion protection of galvanized st...

Hybrid sol–gel coatings for corrosion protection of hot-dip galvanized steel in...

Two distinct organic–inorganic hybrid (OIH) matrices were synthesised using the sol–gel method and deposited on hot-dip galvanized steel (HDGS) by dip-coating. These OIHs, called ureasilicates, U(X), and amino-alcoholsilicates, A(X), were obtained using a functionalised siloxane and five oligopolymers with different molecular weights (MWs). Besides pure OIH coatings, HDGS samples were coated with OIHs doped wit...

Ureasilicate hybrid coatings for corrosion protection of galvanized steel in ch...

Organic-inorganic hybrid (OIH) sol-gel coatings based on ureasilicates (U(X)) have promising properties for use as eco-friendly coatings on hot dip galvanized steel (HDGS) and may be considered potential substitutes for pre-treatment systems containing Cr(VI). These OIH coatings reduce corrosion activity during the initial stages of contact of the HDGS samples with highly alkaline environments (cementitious med...