Terms Of Surface Conditions Research Articles

Statistical modelling and optimization of nanosecond Nd:YAG Q-switched laser scarfing of carbon fiber reinforced polymer

This paper explores the effects of laser scarfing on a CFRP tape consisting of unidirectional carbon fiber with a layup of [(45/0/-45/90)4] sym with a total laminate dimension of 5.952 mm. The laser system used in the experimental investigations consisted of a nanosecond Nd: YAG laser source with an average maximum power of 20 W in a pulsed mode. The material was a with a total laminate of 5.952 mm. The laser process aims to investigate the surface modification by laser ablation. In more details, the effects of scanning speed (550 ÷ 650 mm/s) and frequency (23 ÷ 27 kHz) for three different scanning strategies on the scarfing depth, specimen dimensions (in x and y direction) and surface conditions were studied by full factorial experimental plan. By scarfing, the fibers were either oxidized, partially stripped, stripped and excessively stripped. After the statistical analysis, the best results in terms of surface conditions were achieved with the x-parallel laser scanning strategy, where the presence of excessively stripped fibers was not noticed. The mixed-hatching (MH) mode was the strategy that produced the worst results for the scarfing depth, which can negatively affect the ablation rate, even if it turns out to be the most stable strategy. The best results in terms of scarfing depth and x-y dimensions were achieved with MH mode, and with a scanning speed of 600 mm/s and a frequency of 27 kHz.

Bimodally-porous alumina with tunable mesopore and macropore for efficient organic adsorbents

Since it is of great importance to remove aqueous pollutants for distributing clean water, the adsorption of toxic chemicals on solid adsorbent has been the most practical technique. As one of the widely-accepted design for an adsorbent, hierarchical channel or structurally-connected large and small pore networks take several advantages for application in catalysis and adsorption in liquid or gaseous environment. Mesoporous networks can provide size and shape selectivity for foreign molecule, while macropores can reduce transport limitations and increase the accessibility to the active sites. In this study, we adopted alumina as an adsorbent of organic pollutants due to its easy structural engineering in crystal structure, textural properties, and morphology. As an efficient organic adsorbent, bimodally-porous alumina (BPA) was synthesized to contain mesopores and macropores, which were able to be structured in a separately-controllable manner via solvent-deficient hydrolysis method. The macropores are formed by using polymer beads as a sacrificial template. Additionally, the mesoporous framework is structured through controlling hydrolysis reaction between aluminum alkoxides and water. After calcination, the BPA was pelletized into cylinder or coin shapes for recycling adsorbents without separation and collection steps. We examined the systematic characteristics of the BPA samples, which are associated with the optimal adsorption capability in terms of surface conditions and structural/morphological difference.

Contribution of the Tribal Study to the Effectiveness of the Wool Fiber Composite Compared to Fiberglass Composite Materials

In the field of economic and ecological material research which can replace the composite material currently used in several fields such as glass wool, research leads to a comparison of the mechanical properties and the quality of plates made from recycled materials with those of glass wool, in particular in terms of surface condition and geometric precision thus. In this study, we recycled and used damaged wool fibers in a composite material; the results showed that the new product has mechanical characteristics similar to those of fiberglass composite materials. The recycling of wool fiber reduces the cost of a product made of composite materials, with the possibility of a later study of the machinability of the plates made from this material and its use in various sectors.

Implementation of a low-activation Au-In-Cd decoupler into the J-PARC 1 MW short pulsed spallation neutron source

A silver-indium-cadmium (Ag-In-Cd, or AIC) alloy with a 1 eV high neutron cut-off energy was originaly developed as a decoupler to provide a narrow neutron pulse width with a short tail for the J-PARC 1-MW short-pulsed spallation neutron source. As a result of later studies, gold (Au) was chosen as a substitute for Ag for the production of spare decoupled moderators and reflector in order to reduce residual radioactivity thus easing handling and disposal of the spent moderator and reflector. The decoupler material Au-In-Cd (AuIC) was therefore investigated and developed. To implement it into an actual moderator-reflector assembly many critical engineering issues needed to be resolved with regard to large-sized bonding between AuIC and aluminum alloy A5083 by the hot isostatic pressing process (HIP). The HIP process for AuIC and aluminum was investigated in terms of surface condition, size, and heat capacity. Implementation of an AuIC decoupler into a spare reflector assembly was successfuly achieved and will result in a remarkable reduction of radioactivity compared to AIC without sacrificing neutronic performance.

Thin Surface Layers of Iron-Based Alloys Deposited by TIG Hardfacing

Hardfacing layers developed by tungsten inert gas (TIG) surface melting on commercial purity titanium placing with a mixture of Fe, C and Si powders under two different traverse speeds (1 mm/s and 2 mm/s) and energy input of 1080 J/mm in an argon gas environment were investigated in terms of surface condition, microstructure, hardness and wear of the processed tracks. The surface appearance of treated layers was found to be free from any obvious defect. The TIG hardfacing layer produced dendritic structure due to dissolution of preplaced powder in the Ti melt. A maximum microhardness value of 630 HV 0.5 kgf was found on the surface layer processed with lower speed which was 2.5 to 3.5 times higher than the base material. Ball-on-plate wear tests exhibited better performance of the hardfacing layer than the untreated CP-Ti which is attributed to the presence of carbides and silicides in the Ti melt.

Wind tunnel simulation of a wind turbine wake in neutral, stable and unstable wind flow

Measurements of mean velocity, Reynolds stresses, temperature and heat flux have been made in the wake of a model wind turbine in the EnFlo meteorology wind tunnel, for three atmospheric boundary layer states: the base-line neutral case, stable and unstable. The full-to-model scale is approximately 300:1. Primary instrumentation is two-component LDA combine with cold-wire thermometry to measure heat flux. In terms of surface conditions, the stratified cases are weak, but there is a strong 'imposed' condition in the stable case. The measurements were made between 0.5D and 10D, where D is the turbine disk diameter. In the stable case the velocity deficit decreases more slowly; more quickly in the unstable case. Heights at which quantities are maximum or minimum are greater in the unstable case and smaller in the stable case. In the stable case the wake height is suppressed but the width is increased, while in the unstable case the height is increased and the width (at hub height) reaches a maximum and then decreases. The turbulence in the wake behaves in a complex way. Further work needs to be done, to cover stronger levels of surface condition, requiring more extensive measurements to properly capture the wake development.

Joining with Electrochemical Support: Cold Pressure Welding of Copper – Weld Formation and Characterization

Cold pressure welding is a versatile process that can be used to weld most metals. It is, however, difficult to achieve a weld at room temperature through the application of pressure. As in every welding process, several different parameters have to be considered: the metals to be welded and their properties in terms of surface condition, cleanliness, strength of the metal, and so on. The surface condition and surface preparation methods are the most important parameters, since the cold weld is based solely on the contact between the two metal surfaces that are involved. Joining with electrochemical support (ECUF) is a new approach that overcomes most of the current process barriers and limitations through optimized electrochemical surface treatment and an improved process technology based on a pilger roll. This paper provides an overview of the ECUF process and current research results on the pressure welding of pure copper (CW004A). The formation of the weld has been investigated and the welding interface characterized in respect of its microstructure.

Influence of the Manufacturing Process on Corrosion Behavior of Soda‐Lime‐Silicate Glassware

The reaction of soda‐lime‐silicate glassware with model cleaning solutions gives rise to a systematic pattern of inhomogeneous corrosion. This corrosion is not uniform on the entire surface, but is localized only to certain regions of the glassware. The surface composition, as determined by X‐ray photoelectron spectroscopy, and the microstructure, as characterized by optical and scanning electron microscopy, vary considerably in different regions of the glassware. The visibly heterogeneous corrosion pattern, which correlates with the compositional and structural inhomogeneities, is explained in terms of surface conditions that exist during different stages of glass manufacturing. The role of sodium disilicate in solution is also explored for promoting inhomogeneous glass corrosion.

Characteristic features of laser-nitrided surfaces of two titanium alloys

Trails of IMI115 commercial purity titanium (CP-Ti) and IMI829 alloys, glazed in a pure nitrogen environment using a 1.35 kW CO 2 laser beam with different specimen speeds, have been characterized in terms of surface conditions, hardness, melt depth and microstructure. Rippling marks and porous edges were found in all the trail surfaces. Pores and cracks along the width of the trails were evident. Cracks were observed to be connected with pores, and they were found to propagate down the melt depth where they were arrested close to the heat-affected zone. The cracks were found to increase in number with increasing speed. The melt region consists of a dendritic structure of TiN, and the dendrites were more prevalent in CP-Ti than in IMI829. The melt profile was irregular in shape, and the generation of a differential capillary flow pattern as well as the precipitation of TiN in the melt are considered to be responsible for this phenomenon. A very steep hardness profile was produced in all the trails. Nitrided CP-Ti and IMI829 both had a high Vickers surface hardness of around 2000 HV. The precipitation of TiN dendrites is thought to increase the hardness of the melt in general and, in particular, the larger dendrites developed a higher hardness in CP-Ti than in IMI829.

Effectiveness of four methods for preparing root canals: A scanning electron microscopic evaluation

In this study, 140 curved root canals of extracted teeth were prepared by one of the four following methods: 1) hand preparation using K files and H files alternately; 2) automated preparation using a sonic air handpiece fitted with Rispisonic and Helisonic instruments or 3) fitted with Shapersonic instruments; or 4) mechanical preparation using Canal Finder instrumentation. The roots were ground saggitally and the specimens were evaluated by scanning electron microscopy. The shaping and cleaning effectiveness of the preparation methods were assessed in terms of surface condition of the canal walls at the level of their coronal, middle, and apical thirds. Each canal was evaluated according to a scale from 1 to 4. A statistical analysis was used to indicate any significant difference in surface condition among the four methods. The results obtained with the manual method were similar to those gained from the Canal Finder method, without any difference between the three parts of the canal. The surface condition of the canals prepared with both Sonic Air methods was better in the coronal and middle thirds than in the apical third where pulp residues were noticed.

On the generation of transient capillary waves on the surface of laser irradiated targets

Trails of IMI115 commercial purity titanium (CP-Ti) and IMI829 alloys, glazed in a pure nitrogen environment using a 1.35 kW CO2 laser beam with different specimen speeds, have been characterized in terms of surface conditions, hardness, melt depth and microstructure. Rippling marks and porous edges were found in all the trail surfaces. Pores and cracks along the width of the trails were evident. Cracks were observed to be connected with pores, and they were found to propagate down the melt depth where they were arrested close to the heat-affected zone. The cracks were found to increase in number with increasing speed. The melt region consists of a dendritic structure of TiN, and the dendrites were more prevalent in CP-Ti than in IMI829. The melt profile was irregular in shape, and the generation of a differential capillary flow pattern as well as the precipitation of TiN in the melt are considered to be responsible for this phenomenon. A very steep hardness profile was produced in all the trails. Nitrided CP-Ti and IMI829 both had a high Vickers surface hardness of around 2000 HV. The precipitation of TiN dendrites is thought to increase the hardness of the melt in general and, in particular, the larger dendrites developed a higher hardness in CP-Ti than in IMI829.