Papers by Keyword: Surface Treatment

Abstract: 3-Ethyl-3-benzoxy-methyl oxacyclobutane (TCM 104) and 3,4-epoxy-cyclohexyl carboxylic acid-3',4'-epoxy-cyclohexyl methyl ester (UVR 6110) as active diluents, a mixture of modified epoxy-acrylate and modified polyester acrylate in a certain proportion of oligomer, triaryl sulfonium hexafluorophosphate as cationic photoinitiator, irgacure 184 as free radical photoinitiator, and high-pressure mercury lamp as radiation source, and then the compound formula of free radical and cation hybrid photo-curing were prepared and further coated on the hot-dipped aluminum-zinc steel plate. After curing, the passivation film was characterized by neutral salt spray testing, FT-IR spectroscopy and electrochemical properties along with other relative evaluation criterions. The passivation film of this hybrid system can be cured at an energy of 600 mJ/cm², and its performances are comparable to those of current water-based passivators.

Abstract: The results of researches of wood burning parameters and influence of fire-retardant substances on them are given. Studies have shown that the process of heat insulation of a wooden structure is the formation of soot-like products on the surface of natural combustible material. Under the action of the burner flame on the protected sample treated with impregnating solutions based on a mixture of ammonium phosphate with antiseptic, the temperature of gaseous combustion products was 230 oC, and weight loss did not exceed 9%, while wood treated with a composition of urea and phosphoric acids and starch showed temperature of 160 oС with a weight loss of 3.6%. It is established that fire protection by coatings provides a low rate of burnout of wood samples and with increasing temperature exposure and translates into a non-flammable material that does not spread the flame on the surface.

Abstract: Despite the advanced development in the field of creating new hard-alloy and ceramic tool materials, the use of modern high-speed steels has not yet lost its relevance, and it is especially true for the production of small batches of costly specialized tools, especially since modern strengthening technologies can make it competitive. For example, additive production systems associated with laser or electron beam manufacturing methods create products, including Ti-6Al-4V alloy, with low surface quality, and it is still necessary to apply the additional cutting treatment. The features of milling titanium alloy obtained by the electron beam melting method were revealed. It is determined that the force parameters differ from those in the processing of metal obtained by traditional technologies. Thus, the component of cutting tangential force F_T increases by approximately 15%. At the same time, a 20% drop in the radial force F_R observed

Abstract: When fabricating fiber metal laminates, the joining between the metal sheet and the composite is affected by the chemical and mechanical properties at the interface. To this end, this study investigated the influence of different induced-surface characteristics of AZ31B magnesium alloy sheets when joint with glass fiber reinforced polyamide 6. The treatments, carried out to modify the AZ31B surfaces, were annealing, sandblasting, and their combination. The mechanical and chemical interlocking at the metal-composite interface was assessed in terms of macroscopic and microscopic defects as well as lap shear strength. The obtained results indicated that the joint effectiveness was mainly affected by the annealing treatment, which induced both a chemical and morphological modification of the surface. The formed oxide layer at the interface, combined with surface topography modification, were capable to increase the lap shear strength up to 87%.

Abstract: This study focused on the feasibility of utilizing waste rubber tyre as coarse aggregate in concrete as a partial replacement of brick aggregate (BA). Within this context, fresh and hardened properties were investigated on concrete made with three different percentage replacements (0, 10 and 20% by volume) of BA by waste rubber tyre aggregate (WRTA). The WRTA was washed with tap water (H₂O) and treated with 20% sodium hydroxide (NaOH) for 2 hours. It was found that the workability and dry density of concrete decrease with an increasing percentage of WRTA. In case of mechanical properties, the compressive strength decreases with the increasing content of both treated and untreated WRTA. The maximum decrease was observed for 20% of both treated and untreated WRTA, which was 41-46% for treated and 47-54% for untreated lower than the reference concrete for all curing ages. It was observed that the concrete made with tyre treated with NaOH provides better strength than untreated tyre aggregate. This behavior could be attributed to the better bonding between cement paste and rubber aggregates as a result of the increased surface roughness by NaOH.

Abstract: The effects of the peening conditions on the surface characteristics and fatigue strength of stainless steel were investigated by microshot peening (MSP). In recent years, MSP technology has attracted attention. The use of MSP technology with minute media has become more widespread in consideration of the reduction of the notch effect in the material surface. However, the effect of MSP technology on stainless steel has not been much studied. In the present study, an air-type machine was used. The media used was high-carbon cast steel (490 HV) and Fe-Cr-B alloy (1130 HV), with an average diameter of 0.1 mm. The peening time was in the range of 0 - 100 s. Four types of stainless steels, SUS304, SUS304L, SUS316, and SUS316L, were tested. The workpieces were annealed at 1100 K for 1.2 ks in air. In the measurement of fatigue strength, the workpieces were machined in hour-glass shape. As the results, surface roughness of the workpieces treated by MSP was small. Work hardening was evident to the depth of approximately 0.2 mm from the surface. This depth was about twice the diameter of shot media. However, the effect of the peening time on the hardness distribution was not large. The compressive residual stress was added in the surface vicinity. It is assumed that the fatigue limit had increased because the work hardened layer was formed near the workpiece surface.

Abstract: The aim of this study is to analyze how the fatigue behavior of DMLS built AlSi10Mg may be affected by heat and surface treatments. A three-by-three factorial plan has been arranged for this purpose. Particularly, regarding the heat treatment, three levels were considered (as built, age hardening and stress relief), whereas, for the surface treatment, three levels were investigated (micro shot-peening, micro shot-peening plus fine blasting and DMLS production, machining and lapping). Ten specimens per type were built with vertical orientation and with a cylindrical smooth geometry. 90 samples were tested on a four-point rotating bending machine, aiming at the determination of S-N curves in the finite life domain. The experimental results were statistically processed and compared. The outcome was that heat treatment significantly affects the fatigue response and stress relief may have a detrimental impact. Fractographic studies were performed as well, to individuate the crack initiation points. Finally, density measurements were carried out to quantify the porosity level.

Abstract: During the implantation process, an expandable balloon stent undergoes a change in mesh shape with a high strain rate. Permanent mesh shape changes to the stents indicate plastic deformation has occurred. On a micro-scale, plastic deformation has significant influence when interacting with the soft tissue of human blood vessels. This experimental study aims to investigate the effect of surface treatment and cutting orientation on the changes in surface roughness that definitely occurs when a stent deployed. To study the effect of surface treatment, two types of surface treatment were applied after surface polishing, i.e. etching and electropolishing. Surface polishing is carried out to enable microscopic observation. As for examining the effect of cutting orientation, the plate is cut in lateral and longitudinal orientation against the predicted-rolling direction of 316L sheet-type of stainless steel. An intermittent tensile test is conducted to obtain information about the changes in surface roughness. The surface observation is carried out three times on a similar surface of testpiece after reaching plastic deformation. The experimental study shows that the orientation of raw material has an insignificant effect on the changes in stent surface roughness. As for the surface treatments, electropolishing tended to decrease the tensile property of material.

Abstract: Fireproof coatings at the time of operation of the building structure is a separate and complex task, covering both the stages of the process protection from moisture, and subsequent fire protection formed during the swelling of the coating. They have been proven to create a layer of material on the surface that prevents moisture from penetrating the wood when the destruction of the coating begins. This makes it possible to determine the effect of flame retardants and the properties of the protective compositions on the process of slowing down the rate of water absorption. The process of moisture transfer by flame retardant coating in the presence of a polymeric shell is simulated, the diffusion and mass transfer dependences are obtained, and the diffusion coefficient is determined, which is 7.08·10^-12 m²/s, which allow to obtain a change in the dynamics of moisture upon washing out of the flame retardant. The results of determining the weight loss of the coating sample during exposure to water indicate the ambiguous effect of the nature of the leaching agent. In particular, this implies the availability of data sufficient for qualitatively conducting the process of inhibition of moisture diffusion and detection on its basis of the moment from which the fall of the coating efficiency begins. Features of slowing down the process of moving the moisture to the material that is treated with flame retardant, are in several aspects. Namely, the use of water-insoluble flame retardants and other components, as well as polymer binder, which are characterized by the formation of polymer shell on the surface of the wood.

Abstract: The aim of this work is the improvement of mechanical properties of oil palm fiber (OPF) reinforced polylactic acid (PLA) composites by using sodium hydroxide (NaOH) treatment. NaOH concentrations (0 to 15 %wt.) and treatment times (0 to 30 min) were varied to determine the suitable condition for surface treatment of OPF. Aspect ratio (L/D) and the surface texture of OPF were investigated by using an optical microscope and scanning electron microscope (SEM), respectively. The result suggested that the most suitable condition for surface treatment of OPF was NaOH concentration of 10 %wt. at immersion time of 20 min. Aspect ratio and surface roughness of OPF increased after alkali treatment. For the effect of alkali treatment on the mechanical properties of the composite, it was evaluated by tensile and impact testings and SEM technique. The results showed that surface treatment with NaOH led to enhance mechanical properties of the composite due to improvement of interfacial adhesion.