Chemical Surface Treatment Research Articles

Preparation of the surface of parts from titanium alloys for gluing with parts from polymer composite materials

A method has been developed for preparing the surface of titanium alloys, which provides an increase in the strength characteristics of titanium–composite adhesive joints. When preparing the surface of parts made of titanium alloys, it is not enough to use only mechanical treatment, and when combined with chemical surface treatment, the formation of strong bonds is possible. Surface preparation is carried out by forming a relief structure by applying corrugations on the machine, followed by removal of the oxide film and the formation of a high degree of microroughness by etching in a mixture of acids. Preparing the surface of titanium surfaces with a new method allows minimizing the influence of the human factor, improving the adhesion characteristics of the surfaces of parts, and increasing the time interval between mechanical preparation and gluing. Studies have been carried out to determine the ultimate strength in shear, bending, torsion, compression, tension, as well as to determine the effect of the gap in time intervals between mechanical surface preparation and gluing on the strength characteristics of the adhesive joint on titanium–composite samples with different titanium surface preparation. The analysis of the influence of methods of surface treatment of parts made of titanium alloys on the strength of the adhesive joint is carried out, taking into account the influence of thermal exposure in vacuum conditions, simulating the operation of a spacecraft in space conditions.

Improving the thermal conductivity of natural rubber by constructing three-dimensional thermal conductivity networks and chemically bonded filler-matrix interaction

It has become the mainstream way to take advantage of the new carbon materials to modify polymer matrix to prepare thermal interface materials (TIMs) with excellent comprehensive properties for the modern electronic packaging materials. Yet, how to make full use of the properties of new carbon materials is still facing the severe challenges. Herein, thiol-functionalized carbon nanotubes/natural rubber (CNTs-SH/NR) TIMs with three-dimensional networks (3D) and covalently bonded filler/matrix interactions were fabricated through the surface chemical treatment as well as ice-templated approach. The results proved that CNTs-SH/NR TIMs could achieve a high through-plane thermal conductivity of 1.22 W m −1 K −1 with CNTs-SH content was 25 wt%. Simultaneously, it showed sensitive heat response capacity. The improvement of filler/matrix interface and 3D networks were of great importance in abating the total thermal resistance. Moreover, the method provide a novel route to design high-performance thermal conductive TIMs and apply for the thermal management of electronics. • CNTs fillers with dual functions of thermal conductivity and enhancement are prepared by chemical etching and surface modification. • The covalent bonding between CNTs and NR is helpful to further improve the thermal conductivity of NR TIMs. • A thermal conductivity of 1.22 W m -1 K -1 is achieved for NR based TIMs.

Influence of chemical machining on axial fatigue behaviour of electron beam melted Ti6Al4V parts

Additive manufacturing of titanium parts is a technology widely adopted and investigated because of the great demand of advanced components from aerospace, biomedical and automotive industry. Among the technologies available for additive manufacturing, Electron Beam Melting can produce high density components in short time, however surface quality is poor and incompatible with industrial requirements. For this reason, surface finishing is generally required. In this work, a chemical surface treatment by means of chemical machining has been investigated on specimens built according to axial fatigue standard geometry, and their fatigue behaviour has been correlated with surface quality.

Effect of different chemical surface treatments on interfacial compatibility and properties of polyhydroxyalkanoates/coffee grounds composites

AbstractThe aim of this study was to improve the interfacial compatibility of polyhydroxyalkanoates (PHA) with coffee grounds (CGs) in order to enhance the properties of the composites. Three different methods including alkali, silane, and alkali/silane treatments were used for the surface modification of CGs to construct compatible interfaces and were compared to obtain the most effective modification method. The results showed that the alkali treatment increased the tensile strength, flexural strength, and elongation at break of the composites by 12.61%, 9.81%, and 3.81%, respectively. The silane coupling agent treatment increased the tensile strength, flexural strength, and elongation at break of the composites by 15.51%, 17.78%, and 14.00%, respectively. The mechanical properties of the composites were further improved by the alkali/silane treatment. The three surface treatments improved the compatibility of CGs with the PHA matrix to different degrees, with the alkali/silane treatment being more effective than treatment with alkali or silane coupling agent alone. In addition, the different surface treatments also improved the thermal properties and water resistance of the composites to different degrees. Mechanisms have been proposed to interpret the observed changes in mechanical and thermal properties as a result of fiber treatments by performing SEM, XRD, and FTIR tests on CGs. It is expected that alkali/silane treatment surface modification methods have broad application prospects in the preparation of modified CGs reinforced polymer composites.

Suitability of Surface-Treated Flax and Hemp Fibers for Concrete Reinforcement

The use of vegetable fibres as a sustainable alternative to non-natural sources of fibres applied for concrete reinforcement has been studied for over three decades. The main issues about plant-based fibres pointed out by other authors are the variability in their properties and concerns about potential high biodegradability in the alkaline pH of the concrete matrix. Aiming to minimise the variability of flax and hemp fibres, this research compares a range of chemical surface treatments, analysing their effects on the behaviour of the fibres and the effects of their addition to concrete. Corroborating what has been found by other authors, the treatment using NaOH 10% for 24 h was able to enhance the properties of hemp fibre-reinforced concrete and reduce the degradability in alkaline solution. For flax fibres, a novel alternative stood out: treatment using 1% of stearic acid in ethanol for 4 h. Treatment using this solution increased the tensile by 101%, causing a minor effect on the elastic modulus. Concrete mixes reinforced with the treated flax fibres presented reduced thermal conductivity and elastic modulus and increased residual tensile strength and fracture energy.

Comparative study on thermogravimetric analysis of banana fibers treated with chemicals

Natural fibers have shown to have exceptional properties and as excellent reinforcing agents in composite materials, both of which are solutions to environmental problems. However, due to its hydrophilic nature, it tends to swell and degrade when exposed to moisture. Therefore, it will result in poor interfacial bonding with polymer matrix, and poor mechanical and thermal properties. Surface chemical treatment of fibers improved the properties of the fibers by destroying the hydrogen bond in the fiber network. An investigation has been made to study the effects of thermogravimetric analysis (TGA) on three different chemically treated banana fibers from Island of Borneo. TGA is an effective technique for performing thermal analysis. In this technique, the mass of a certain material that needs to be analyzed is observed in relation to temperature. The banana fibers obtained were subjected to chemical treatment of 5 wt% of sodium hydroxide (NaOH), 5 wt% of potassium hydroxide (KOH), and 5 wt% of calcium carbonate (CaCO3) for 24 h. The thermogravimetric analysis shows an improved thermal stability after the fibers were being treated. Besides that, it shows higher thermal stability with sodium hydroxide treated banana fiber and the least weight loss of 48% compared to other treated banana fibers.

Comparative Mechanical Study of Pressure Sensitive Adhesives over Aluminium Substrates for Industrial Applications.

The use of adhesives for fixing low-weight elements is showing increasing interest in the industry, as it would reduce the weight of the assembly, costs, and production time. Specifically, the application of pressure-sensitive adhesives (PSAs) to join non-structural naval components to aluminium substrates has not yet been reported. In the present work, a study of the mechanical behaviour of different double-sided PSAs applied on bare aluminium alloy substrates is performed. The influence of surface roughness, surface chemical treatments, and the matrix of the adhesives is studied through different mechanical tests, such as shear, T-peel, and creep. The application of an adhesion promoter improved the mechanical behaviour. Low roughness substrates provided better performance than ground samples. Acrylic foam adhesives were subjected to creep tests, whose results were fitted to a simple mathematical model, predicting the fracture time as a function of the applied load.

The Effect of Morpholine on Composite-to-Composite Repair Strength Contaminated with Saliva.

The aim of this study was to specifically explore the effects of morpholine on chemical surface treatments of aged resin composites contaminated with saliva to new resin composite repair strength. One hundred and thirty five resin composite specimens were fabricated and thermocycled to replicate an aged resin composite. These aged resin composites were randomly separated into nine groups (n = 15) depending on the various surface contaminants and surface treatment techniques. These groups were as follows: group 1-no surface treatment; group 2-no saliva + adhesive agent; group 3-no saliva + morpholine + adhesive agent; group 4-no saliva + morpholine; group 5-saliva; group 6-saliva + adhesive agent; group 7-saliva + morpholine + adhesive agent; group 8-saliva + morpholine; and group 9-saliva + phosphoric acid + adhesive agent. A mold was covered on the top of the specimen center and then filled with resin composite. The shear bond strengths and failure modes were examined. The collected data was analyzed using one-way ANOVA, and the significance level was determined using Tukey's test. Group 5 (3.31 ± 0.95 MPa) and group 6 (4.05 ± 0.93 MPa) showed the lowest bond strength statistically, while group 3 (23.66 ± 1.35 MPa) and group 7 (22.88 ± 1.96 MPa) showed the most significantly high bond strength. The bond strength in group 2 (16.41 ± 1.22 MPa) was significantly different from that in group 1 (9.83 ± 1.13 MPa), group 4 (10.71 ± 0.81 MPa), and group 8 (10.36 ± 1.53 MPa), while group 9's (17.31 ± 1.48 MPa) SBS was not significantly different. In conclusion, the application of morpholine on aged resin composite with or without contamination with saliva prior to the application of the adhesive agent increased the bond strength of aged resin composite repaired with new resin composite (p < 0.05).

The effect of surface treatments on the interlaminar shear failure of GLARE laminates subjected to pre‐cyclic thermal loads

AbstractIn this study, both the individual and combined effect of thermal cycling and surface treatment on the interlaminar shear strength (ILSS) of glass laminate aluminum‐reinforced epoxy (GLARE) 3/2 sheet material are investigated experimentally. Three kinds of surface treatments including sandpapering, degreasing and both degreasing and sandpapering are applied to AA6061‐T6 sheets before manufacturing of hot‐pressed GLARE 3/2 sheet material. Two different cyclic thermal conditions, which are referred to the flight characteristics of a typical transport category aircraft, are then applied to short‐beam GLARE specimens by changing temperature limits and keeping the number of cycles the same. Three‐point bending tests are lastly performed to examine the effects of surface treatments on the ILSS of GLARE laminates under pre‐cyclic thermal conditions by comparing with the specimens under acyclic condition at room temperature. The results show that the ILSS of surface‐treated laminates have an increase by between 29% and 73% against untreated ones according to the cyclic thermal profile. If sandpapering and degreasing apply together as a combined mechanical–chemical surface treatment process, then ILSS is totally preserved or reduced by only 4% under certain thermal pre‐cyclic conditions.

Laser-induced contamination deposit growth mechanisms on space optics

Lasers in space often suffer from light absorbing deposits forming inside the resonator. This effect is commonly called laser-induced contamination (LIC), and its mechanism can be compared with laser chemical vapor deposition. LIC experiments were carried out in a dedicated vacuum chamber using a q-switched 355-nm laser, hafnia- or silica-coated fused silica samples and contamination by epoxy adhesive outgassing, or toluene vapor in vacuum. The typical deposit formation was observed at different experimental conditions and analyzed by in situ laser-induced fluorescence imaging and ex situ white light interference microscopy. We determined the average growth rate during the first growth stage (bump-shaped growth) and analyzed it as a function of the laser fluence, sample nature, and used contamination. The data show that the band gap of the sample is important for the LIC process in the first growth stage. The light absorbed in the sample leads to a temperature rise that drives the deposit growth. This knowledge opens a new pathway to minimize LIC that is complementary to studies that aim to reduce the adsorption of contaminant molecules by making chemical surface treatments.

Evaluation of Zirconia Surface Roughness after Different Surface Treatment with Sandblasting, Hydrofluoric Acid Etching, and Combination Treatment

Zirconia is one of the materials used in prosthetic restoration because of its better physical, mechanical, chemical, and biological properties. The surface treatment for zirconia can be mechanical, with grinding, sandblasting, and laser or chemically, with silane and etching. The combination of chemical and mechanical surface treatment can increase the surface roughness so that the bonding with the resin cement also increases. The study aims to examine the zirconia surface roughness after different surface treatments. This study used 25 zirconia samples in 10x10x2 mm square-shaped, divided into five groups. Group 1 treats sandblasting as a control. Group 2 sandblasting then etching with 9.5% hydrofluoric acid at 25°C for 60 minutes. Group 3 sandblasting then etching with 9.5% hydrofluoric acid at 100°C for 1 minute. Group 4 etching with 9.5% hydrofluoric acid at 25°C for 60 minutes. Group 5 etching with 9.5% hydrofluoric acid at 1000C for 1 minute. The samples were cleaned with an ultrasonic cleaner and tested using a profilometer. The data test by using the ANOVA test and T-test. The highest surface roughness was the combination of sandblasting with 9.5% hydrofluoric acid etching at 25°C for 60 minutes. The lowest was 9.5% hydrofluoric acid etching at 100°C for 1 minute. ANOVA statistical analysis with a p-value <0.05 ((8.4051 x 10-12) indicates that the test was significant. The result of this study was the combination of surface treatments resulted in higher surface roughness. Duration of the etching time affected the increase of zirconia surface roughness.

Fatigue behavior of hybrid eco-composites: A review

Multifunctionality of composites has gained popularity, primarily through the hybridization of polymer composites for augmented performance. In this case, hybridization is ensured by adding fibrous reinforcement of different materials. There are a multitude of characteristics which can be enhanced due to hybridization. The synthetic reinforcements respond to uncontrolled carbon footprints, so we cannot claim them as sustainable. Hence, scientists have been discovering new solutions in sustainable eco-composites (with natural reinforcements) to tackle the environmental challenge. It is reported that albeit the natural fibres are eco-friendly, but they often lack in desired properties and hence find difficulty to enter the market. To achieve desired properties, several limitations of natural fibre, such as hydrophilic qualities, can be addressed by different surface alterations and chemical treatment procedures. Post the fourth industrial revolution, the rising concern about environmental issues has led an increased interest in natural fibre hybrid composites (also called as hybrid eco-composites). Such composites are composed of eco-friendly fibres or a combination of synthetic and natural fibres as a reinforcing material which makes it capable for multifunctional applications. Natural fiber reinforced composites have a great potential of cost per unit weight reduction and renewability over applications such as door panel, seat backs, dashboard, noise insulation panel, railing, bridge, and roof tiles. The prior art reveals that these composites have low fatigue strength which limits itself in structural application in comparison to its competitors, the synthetic composites. This means hybridization could result in synergy of advantages of each of the constituents leading to high fatigue strength, better load carrying, eco-friendly, and a low-cost structure. This review provides an overall insight on various hybrid eco-composites including their mechanical properties, fatigue behavior and its applications.

CNT toughened aluminium and CFRP interface for strong adhesive bonding

This study presents a simple technique for strengthening the adhesive-bond strength between aluminium (Al) substrate and carbon fibre reinforced polymer (CFRP) utilising resin pre-coating (RPC) with carbon nanotubes (CNTs). The CNT-containing RPC solution with 90 ​wt% acetone and 10 ​wt% resin (without hardener) was applied onto Al substrates, where micro-/nano-vertical channels had been created by chemical or mechanical surface treatments to accommodate CNTs. RPC was able to fill all micro-/nano-cavities over the Al substrate surface, then CNTs were pulled into those vertical micro-channels by the capillary action generated from acetone evaporation. Normal epoxy adhesive (resin ​+ ​hardener) was applied after the CNT-containing RPC treatment. CNTs bridging across the interface between the adhesive joint and Al substrate and sealing of micro-/nano-cavities by RPC effectively enhanced the interfacial shear bond strength between the Al substrate and CFRP by 30–100% depending on the Al substrate surface profiles. Al substrates with two different chemical treatments were compared in this study for the effectiveness of CNT interfacial reinforcement. Results from a steel substrate after sandblasting were also included for comparison.

Ni/Pd-based ohmic contacts to p-GaN through p-InGaN/p+-GaN contacting layers

Specific contact resistance to p-GaN was measured for various structures of Ni/Pd-based metals and thin (20–30 nm thick) p-InGaN/p+-GaN contacting layers. The effects of surface chemical treatment and annealing temperature were examined. The optimal annealing temperature was determined to be 550 °C, above which the sheet resistance of the samples degraded considerably, suggesting that undesirable alloying had occurred. Pd-containing metal showed ~35% lower compared to that of single Ni. Very thin (2–3.5 nm thick) p-InGaN contacting layers grown on 20–25 nm thick p+-GaN layers exhibited one to two orders of magnitude smaller values of compared to that of p+-GaN without p-InGaN. The current density dependence of , which is indicative of nonlinearity in current-voltage relation, was also examined. The lowest achieved through this study was 4.9 × 10–5 Ω·cm2 @ J = 3.4 kA/cm2.

E. Globulus Vessel and Fibre Chemical Analysis

Hardwood species have a complex cellular structure consisting of fibres, vessel elements and parenchyma cells with different chemical compositions. However, the presence of vessels with significant dimensions in their structure is a recurrent problem in the operation of industrial UWF paper printing. Since the 1980s, vessel picking and ink refusal are problems that paper professionals have tried to solve, but solutions for these have not yet been fully found. If vessels are concentrated in a stream, they can be pre-treated (e.g., by mechanical refining) and reincorporated into the pulp. Other strategies aim at vessel enzymatic and/or chemical passivation and sheet surface chemical treatment, altering the vessel adhesion to the fibre network. This requires vessel concentration at laboratorial level for proper chemical studies, such as FE-SEM, μ-XPS, TOF-SIMS and μFTIR. The main objective of our experimental study was to examine bleached kraft pulp E. globulus vessel and fibre composition. For this we performed EDX and μ-FTIR analysis on both fibre and vessel elements, and obtained the carbohydrate composition, the total acids content, the hexenuronic acids content and the zeta potential.
 Keywords: E. globulus, vessel, EDX, μ-FTIR, sugar content, zeta potential

Effect of Surface Chemical Treatment of Himalayan Nettle and Investigation of Surface, Physical and Mechanical Characteristics in Treated Nettle Fibre

Effect of Surface Chemical Treatment of Himalayan Nettle and Investigation of Surface, Physical and Mechanical Characteristics in Treated Nettle Fibre

Effect of surface treatment on the performance of composite‐composite and composite‐metal adhesive joints

AbstractThe use of Fiber‐Reinforced Polymer Composites (FRPCs) in automotive, aerospace, and naval applications has increased significantly due to the requirement for a high performance‐to‐weight ratio. One the issue in using composite parts is their joining to the metal parts in the global structure. Several joining techniques such as mechanical joining, adhesive, vibration joining, and hybrid joining are used for this purpose. Being lighter in weight and lower in cost in comparison to other techniques, adhesive bonding is mostly used for composite‐composite and composite‐metal joining. To achieve reliable adhesive joining, surface preparation of the joining substrates is of utmost importance. Though the effect of physical surface treatments on the performance of joints has been reported in the literature, however, the effect of chemical surface treatment of composites on the mechanical performance of adhesive joints was rarely studied. In this article, the effect of chemical treatment (alkaline permanganate), of the composite surfaces on the single lap shear strength and Izod impact strength of composite‐composite and composite‐metal adhesive joints is reported. The results showed that the chemically treated joints demonstrate a significant improvement in these properties.

Investigating Features and Output Correlation Coefficient of Natural Fiber-Reinforced Poly(lactic acid) Biocomposites

Polylactic acid (PLA) material has the potential to be applied in various industrial fields, but this material has shortcomings in terms of mechanical properties, especially mechanical strength, due to brittleness nature of PLA. The manufacture of PLA composite material with the addition of natural fibers as a reinforcing phase is one of the methods to increase the impact strength and maintain the biodegradable properties of the material. However, in theory, there are many factors that affect the mechanical properties of composite materials, thus making the mechanical properties of composites more complex than monolithic materials. The mechanical properties of these composite materials can be predicted using deep learning by paying attention to the relationship between factors, and between factors and their mechanical properties. This relationship has an important role in creating a predictive model with good accuracy. Therefore, correlation analysis is an important thing to do. Correlation analysis was applied using Python programming language to determine the relationship between the impact strength of natural fiber-reinforced PLA biocomposites with its feature information: chemical composition, density, dimensions, surface chemical treatment of natural fibers, matrix-reinforcement volume fraction, and the type of processing used to manufacture the material.

Effect of Surface Treatments on Bond Strength of Resin Cements to Titanium: A Literature Review

Objectives: The aims of this literature review are to provide answers to questions on how to improve bonding between titanium and resin cement and how to further implement, in clinical practice, titanium-resin as an alternative to conventional metal–resin systems.
 Material and Methods: A literature search of PubMed was conducted and eight fulfilled the search criteria, namely mentions of titanium, resin cement, bond strength, surface treatments, and luting agents. These papers were compiled for comparison and evaluated regarding the bond strength achieved with different methods.
 Results: The results strongly indicate that there are possibilities to improve the adhesion methods for titanium–luting agents.
 Conclusions: The combination of micromechanical and chemical surface treatments enhanced the adhesion between different resin cements and titanium. It is important to select the appropriate surface treatments of titanium regarding the type of resin cement that will be used. Utilizing titanium with resin cements for crowns and fixed partial dentures can be recommended for routine clinical use.

The synergy of fiber surface treatment and nanoclay on the static mechanical and tribological behaviors of Palmyra fruit fiber/Montmorillonite nanoclay reinforced polyester hybrid composites

This research paper aims to present the combined effect of fiber surface chemical treatments and Montmorillonite nanoclay addition on the mechanical and tribological properties of Palmyra fruit fiber reinforced polyester composites. The polyester composite specimens are made of untreated and chemically surface treated Palmyra fruit fiber as primary reinforcement and Montmorillonite nanoclay as secondary reinforcement. The mechanical properties such as tensile, flexural, and impact behaviors and tribological properties such as specific wear rate and coefficient of friction are evaluated. The results are compared with specimens made without Montmorillonite nanoclay. The worn surface morphologies of the wear-tested samples are analyzed through scanning electron microscopic images to study the various wear mechanisms that persisted.