P. Puomi, H.M. Fagerholm, J.B. Rosenholm and R. Sipilä
The performance of different pretreatment‐primer systems for hot‐dip galvanized (HDG) and Galfan coated steel has been studied. The materials were pretreated with three…
Abstract
The performance of different pretreatment‐primer systems for hot‐dip galvanized (HDG) and Galfan coated steel has been studied. The materials were pretreated with three pretreatment processes; an alkaline oxide pretreatment with either a chromate or a zirconium based post‐rinse, and a zinc phosphating pretreatment. After the pretreatment, the panels were coated with four commercially available primers. The chemically treated substrates were characterized by using ESCA and GD‐OES, and the cured paint films by using FTIR. Paint adhesion of primed panels was determined with a combined cross‐cut and impact test and also with the NMP test. Formability of the panels was tested by T‐bend test and corrosion resistance with a cyclic prohesion test. According to the prohesion test results, primed Galfan coated panels have better edge corrosion resistance than primed HDG panels. Test results also show that the effect of pre‐treatment is not as significant for the corrosion resistance as the effect of primer. However, in the case of zinc phosphated samples, excellent synergistics between the pretreatment and two of the primers was detected.
P. Puomi, H.M. Fagerholm and A. Sopanen
The aim of this work was to investigate which parameters affect the long‐term performance of coil coated galvanised steel sheet. Therefore, the paint adhesion and corrosion…
Abstract
The aim of this work was to investigate which parameters affect the long‐term performance of coil coated galvanised steel sheet. Therefore, the paint adhesion and corrosion resistance of selected painted pre‐treated galvanised steel substrates were studied. The systems investigated included chromate‐free pre‐treatments and primers. The polymer coated panels were tested by using: T‐bend, combined cross cut and adhesion, prohesion and QUV‐A tests. The surface energy of the painted panels was determined by contact angle measurements and outdoor testing of the panels was also initiated. The test results showed that the primer was the most important parameter for painted metal alloy coated steel, but the long‐term performance of the system also depends on the compatibility of all four layers, i.e. substrate, pre‐treatment, primer and topcoat.
Details
Keywords
Jan Stoulil, Martina Anisová, Eva Mistova and Jaroslav Fojt
This work aims to focus on evaluation of the ability of cathodically deposited ZrO2-based coatings to stabilise the surface of silver against tarnishing caused by S2−-based…
Abstract
Purpose
This work aims to focus on evaluation of the ability of cathodically deposited ZrO2-based coatings to stabilise the surface of silver against tarnishing caused by S2−-based species and comparison of these coatings with Cr oxide-based coating.
Design/methodology/approach
The coatings were evaluated using inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), impedance spectroscopy (EIS) and galvanostatic reduction of specimens exposed to H2S vapours.
Findings
The kinetics of deposition were studied and optimum conditions for coating formation were determined. The options of manual application suitable for practical use were studied also. Zr specimens showed better barrier properties than did a chromated specimen. The best properties were observed on a specimen with a manually fast-applied coating. However, Zr coating does not provide as good protection from tarnishing as chromate. The structure of the Cr coating contains species of chromate that oxidize species of S2−.
Originality/value
The paper provides new information regarding the anticorrosive properties of cathodically deposited ZrO2 coating as an alternative to Cr coating for the preservation of silver surfaces.
Details
Keywords
Teofil Jesionowski, Magdalena Nowacka and Filip Ciesielczyk
The purpose of this paper is to characterise the electrokinetic properties of pigments supported on both unmodified and modified silica. The paper describes the preparation of…
Abstract
Purpose
The purpose of this paper is to characterise the electrokinetic properties of pigments supported on both unmodified and modified silica. The paper describes the preparation of hybrid pigments via adsorption of organic dyes on silica supports and determination of the zeta potential and electrophoretic mobility of the materials obtained.
Design/methodology/approach
The materials studied were hybrid pigments obtained as a result of adsorption of two basic dyes: C.I. Basic Red 1 and C.I. Basic Orange 14 and one acidic dye C.I. Mordant Red 3 from solutions of concentrations of 500, 2,000 and 3,000 mg/dm3 on the surface of both unmodified and modified silica supports. The agent used for modification of the silica surface was N‐2‐(aminoethyl)‐3‐aminopropyltrimethoxysilane.
Findings
The modification of the silica surface with aminosilane was found to change, significantly, the electrokinetic character of the inorganic support. This change was interpreted as being due to the ionisation of −NH2 groups from the modifier molecule, which changes the surface charge. Electrokinetic curves of the pigment composites changed considerably as a function of the type and concentration of the organic dye adsorbed.
Research limitations/implications
Only SiO2 supports (unmodified and aminosilane‐grafted) and C.I. Basic Red 1, C.I. Basic Orange 14 or C.I. Mordant Red 3 dyes adsorbed on its surface were evaluated. Other dyes could also be studied.
Practical implications
Measurements of the zeta potential were used to characterise the stability of colloidal dispersions of paints or dyes and to control the stability of paints on storage and their performance on painting and drying.
Originality/value
The paper demonstrates that the measurements of zeta potential permit determination of the optimum conditions for the use of a given pigment. The finding of the change of the zeta potential of a given pigment and so, also its application properties as a result of different functional groups in the dye or the modifying agent molecules.
Details
Keywords
Paula Puomi and Heidi M. Fagerholm
Investigates the adhesion and corrosion performance of selected silanes in primed galvanised steel. For comparison HDG steel was also treated with a chromate‐free and a…
Abstract
Investigates the adhesion and corrosion performance of selected silanes in primed galvanised steel. For comparison HDG steel was also treated with a chromate‐free and a chromate‐containing pre‐treatment. All treated panels were painted with three different primers. Corrosion resistance and paint adhesion of the primed panels were studied. Surface energy of the panels was measured by the contact angle method and is reported in terms of the Lewis base component. The corrosion resistance of the panels depended on the combination of the silane and the primer. Vinyltrimethoxysilane (VS) and γ‐aminopropyltriethoxysilane (γ‐APS) treatments improved the corrosion resistance of polyurethane primed panels. γ‐ureidopropyltrimethoxysilane (γ‐UPS) and VS treatments improved the performance of polyester primed panels. A relationship between the base components and the prohesion test results of γ‐UPS and γ‐APS treated panels was found, which indicates that acid‐base interactions improve the adhesion between these two silanes and the primers. γ‐UPS and γ‐APS treated panels also achieved excellent results in the humidity test with all three polymer coatings.
Details
Keywords
Goksel Saracoglu, Ferhat Ceritbinmez, Vildan Özkan and Ahmet Yapici
This study aims to systematically compare the effect of increasing fiber–matrix interface adhesion and matrix toughness in layered composite materials.
Abstract
Purpose
This study aims to systematically compare the effect of increasing fiber–matrix interface adhesion and matrix toughness in layered composite materials.
Design/methodology/approach
Silane ((3-glycidyloxypropyl) trimethoxysilane) was applied to strengthen the fiber–matrix interface connection in e-glass/epoxy laminated composite material. Using a cationic surfactant, 0.1% multi-walled carbon nanotubes (CNTs) were added to the matrix in two different ways, by with and without chemical functionalization using the vacuum infusion method.
Findings
In the results obtained from the three-point bending test specimens, it was determined that the synergistic effect of silane application and non-functionalized CNT in the matrix was higher in terms of flexural modulus and strength values.
Practical implications
The functionalization of multi-walled CNT did not give the expected results because of reasons such as viscosity increase and agglomeration in the matrix.
Originality/value
In this study, a simple model for normalization and prediction purposes was developed, which allows the determination of the flexural modulus and un-notched flexural strength values from one test result of the notched specimen. A systematic comparison was performed by varying each parameter in the composite material.
Details
Keywords
In this paper a sector will be dealt with, which is lately characterized by an increase in decision‐making in a scientific rationalized way, i.e. the sector of personal social…
Abstract
In this paper a sector will be dealt with, which is lately characterized by an increase in decision‐making in a scientific rationalized way, i.e. the sector of personal social services. Decision‐making is in many cases closely related and attributable to the fact that the social services are increasingly availing themselves of personal computers. An innovation which is most often discussed in terms of technological rationalization and facilitation for the provision of personal social services. This may be the case as long as the computer is used as just another, be it a different, mode, to provide services, e.g. to do away with routine, administrative, and management tasks, such as record keeping (Bloom 1975), information retrieval systems (Rubin 1976), fiscal management (Mutschler 1983), etc.
Pradeep Kumar Mishra and Jagadesh T.
The tensile behavior of additively manufactured nylon-based carbon fiber-reinforced composites (CFRP) is an important criterion in aerospace and automobile structural design. So…
Abstract
Purpose
The tensile behavior of additively manufactured nylon-based carbon fiber-reinforced composites (CFRP) is an important criterion in aerospace and automobile structural design. So, this study aims to evaluate and validate the tensile stiffness of printed CFRP composites (low- and high-volume fraction fiber) using the volume average stiffness (VAS) model in consonance with experimental results. In specific, the tensile characterization of printed laminate composites is studied under the influence of raster orientations and process-induced defects.
Design/methodology/approach
CFRP composite laminates of low- and high-volume fraction carbon fiber of different raster orientations (0°, ± 45° and 0/90°) were fabricated using the continuous fiber 3D printing technique, and tensile characteristics of laminates were done on a universal testing machine with the crosshead speed of 2 mm/min. The induced fracture surface of laminates due to tensile load was examined using the scanning electron microscopy technique.
Findings
The VAS model can predict the tensile stiffness of printed CFRP composites with different raster orientations at an average prediction error of 5.94% and 10.58% for low- and high-volume fiber fractions, respectively. The unidirectional CFRP laminate composite with a high-volume fraction (50%) of carbon fiber showed 50.79% more tensile stiffness and 63.12% more tensile strength than the low-volume fraction (26%) unidirectional composite. Fiber pullout, fiber fracture and ply delamination are the major failure appearances observed in fracture surfaces of laminates under tensile load using scanning electron microscopy.
Originality/value
This investigation demonstrates the novel methodology to study specific tensile characteristics of low- and high-volume fraction 3D printed CFRP composite.
Details
Keywords
Andrew Manning, Anna Fricker and Robert Thompson
The purpose of this paper is to explore the previously unreported phenomenon in which changes occur to the particle size distributions of calcium carbonate fillers, used in…
Abstract
Purpose
The purpose of this paper is to explore the previously unreported phenomenon in which changes occur to the particle size distributions of calcium carbonate fillers, used in papermaking, when exposed to high intensity ultrasound.
Design/methodology/approach
Commercial paper pulps sonicated at a frequency of 20 kHz are found to produce aggregates of their mineral filler constituents. The effects of sonication on isolated long and short fibre, and ground and precipitated calcium carbonate filler systems are also investigated both with and without the presence of dispersants. The findings are supported by particle size analysis and scanning electron microscopy of the sonicated systems.
Findings
It is clearly shown that exposure to high intensity ultrasound induces filler aggregation. However, the effect only occurs when paper fibres and fillers coexist and is not apparent for suspensions of filler only or fibre only slurries. Furthermore, the treatment overrides the effect of dispersants used to keep filler in suspension during the manufacturing process. An accompanying fall in pH with increasing sonication times is also noted and is linked to these changes. It is proposed that radical species produced in the slurries during sonication may explain the observed phenomenon.
Research limitations/implications
The role of pH is not clearly understood and needs further study.
Practical implications
The findings may be of interest in paper manufacture where uniform dispersal of fillers throughout the pulp is of significant importance.
Originality/value
The phenomenon described in this paper has not previously been reported or explored. Further studies may add to knowledge of filler dispersions and their behaviour in papermaking.