cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.6857942.v1
title: Effect of MTMO silane concentration on electrogalvanized steel in the protection against corrosion

description: ABSTRACT Superficial pretreatments based on silanes are one of the prominent alternatives to replace chromates as temporary protectors from the action of aggressive environments to metallic substrates. The barrier effect afforded by the silane film makes porosity, thickness and film homogeneity important issues in the protective effect. In the present work, the influence of the concentration and amount of layers of mercaptopropyltrimethoxysilane (MTMO) applied on electrogalvanized steel on its corrosion behavior was evaluated. Before silane application the substrate was degreased by immersion in toluene for 2 min at 40 ºC. The surface sample was activated by immersion in NaOH 10% p/v and applying a cathodic current density of 0,12 A/cm2, the temperature was controlled at 40 ºC. MTMO was prepared adding 2 or 4 % v/v of MTMO to a distilled water/methanol (3:2v/v, pH adjusted to 4 with acetic acid), and hydrolyzed for 60 min; some samples were coated with 1 layer of MTMO and others with 2 layers. All the coatings were cured at 80 ºC for 10 min. The coating’s porosity was evaluated by cyclic voltammetry and reaction to copper sulphate, its thickness and morphology by SEM-EDS and the corrosion behavior by polarization curves, electrochemical impedance spectroscopy and exposure into a temperature and humidity controlled-chamber. The results showed that the protective capacity afforded by 2 layers of MTMO is higher than that obtained by raising the silane concentration. Besides, the variables under study affect the morphology and the thickness of the protective layer.
DOI: 10.6084/m9.figshare.6857939.v1
title: Carcass and body components of suckling lambs grazing ryegrass and supplemented with legume or concentrate

description: ABSTRACT This research objective was to evaluate the effect of private supplementation with concentrated or legumes, on the carcass characteristics and body components from suckling lambs kept on ryegrass pasture. Twenty seven suckling lambs were used, with about 17 days of age and weighing 9,91±0,594kg, which were distributed in the treatments that corresponded to feeding systems: suckling lambs kept on ryegrass pasture, suckling lambs kept on ryegrass pasture and supplemented with concentrated in private feeder (creep feeding) and suckling lambs kept on ryegrass pasture and supplemented with legume in the private pasture (creep grazing). The concentrate supplement was composed by corn, soybean meal and limestone, and was supplied ad libitum. The supplementary pasture was white clover legume. The experimental design was completely randomized, where the results were submitted to analysis of variance and means compared by Tukey test at 5% of significance level. The gastrointestinal+bile+urine content and the proportion of esophagus were higher (P&lt;0,05) in lambs kept on ryegrass. The liver and large intestine proportions were higher (P&lt;0,05) in lambs supplemented with concentrate. The tested alimentary systems produce carcasses with similar characteristics. The supplementation with legume or concentrate cause changes in body components of suckling lambs grazing ryegrass.
DOI: 10.6084/m9.figshare.6857936
title: Electrochemical characterization of zinc oxide films obtained by anodizing in alkaline medium

description: ABSTRACT Zinc Oxide is a material of particular interest because of its unique optical and electrical properties, which are explored for many applications in optoelectronics and nanoelectronics; and it that can be synthesized economically by the technique of anodization. In this work, the potentiostatic anodization technique was used in dilute NaOH solution, at room temperature, to obtain ZnO anodic films. The morphological and structural properties of the anodized films obtained at different voltages and of the films subjected to heat treatment were characterized by scanning electron microscopy (SEM) and the films were found to be compact, of heterogeneous morphology, and that the particle size was proportional to the applied potential. In addition, electrochemical studies were carried out by applying the Electrochemical Impedance Spectroscopy (EIS) technique to evaluate the electrochemical properties of the films. It was demonstrated that the ZnO films presented a resistive and capacitive behavior, the latter being associated to the presence of a constant phase element with identity coefficient (n) defined slightly lower than unity. The thicknesses of the films were determined by adjusting the experimental results obtained by EIS to an equivalent circuit considering the constant phase element as an ideal capacitor. Based on the parameters analyzed it was concluded that larger layers were applied with greater thickness and less resistance, while at lower potentials the layers tended to be thinner and resistive. On the other hand, it was demonstrated that the applied heat treatment caused a decrease in the electrical resistance of the films, and an increase in the capacitance of the system, with its consequent decrease in thickness, with respect to films without heat treatment, but no differences were found in the electrochemical properties between the thermally treated films.
DOI: 10.6084/m9.figshare.6857936.v1
title: Electrochemical characterization of zinc oxide films obtained by anodizing in alkaline medium

description: ABSTRACT Zinc Oxide is a material of particular interest because of its unique optical and electrical properties, which are explored for many applications in optoelectronics and nanoelectronics; and it that can be synthesized economically by the technique of anodization. In this work, the potentiostatic anodization technique was used in dilute NaOH solution, at room temperature, to obtain ZnO anodic films. The morphological and structural properties of the anodized films obtained at different voltages and of the films subjected to heat treatment were characterized by scanning electron microscopy (SEM) and the films were found to be compact, of heterogeneous morphology, and that the particle size was proportional to the applied potential. In addition, electrochemical studies were carried out by applying the Electrochemical Impedance Spectroscopy (EIS) technique to evaluate the electrochemical properties of the films. It was demonstrated that the ZnO films presented a resistive and capacitive behavior, the latter being associated to the presence of a constant phase element with identity coefficient (n) defined slightly lower than unity. The thicknesses of the films were determined by adjusting the experimental results obtained by EIS to an equivalent circuit considering the constant phase element as an ideal capacitor. Based on the parameters analyzed it was concluded that larger layers were applied with greater thickness and less resistance, while at lower potentials the layers tended to be thinner and resistive. On the other hand, it was demonstrated that the applied heat treatment caused a decrease in the electrical resistance of the films, and an increase in the capacitance of the system, with its consequent decrease in thickness, with respect to films without heat treatment, but no differences were found in the electrochemical properties between the thermally treated films.
DOI: 10.6084/m9.figshare.6857933
title: Porous titanium dioxide coatings synthesized by anodic oxidation

description: ABSTRACT Titanium dioxide is one of the most used materials in heterogeneous photocatalysis due to its commercial availability, low cost, chemical stability, low toxicity and high photocatalytic activity. One of the most efficient and economical methods to obtain TiO2 coatings is the plasma electrolytic oxidation. In this anodization process, a direct current is circulated between a cathode and an anode immersed in an electrolyte solution, at a high voltage that induces the formation of spark discharges on the surface of the anode. In the present work, porous TiO2 coatings were obtained by plasma electrolytic oxidation, using 1 M sulfuric acid as the electrolyte, a Pt cathode, titanium Grade 2 as the anode and a maximum current density of 3250 A m-2. The influence of voltage (90-180 V) and surface finishing (with and without metallographic polishing) on the morphology and crystalline structure was studied. The temporal evolution of voltage and current density were recorded. The morphology of the oxides was observed by scanning electron microscopy, and the crystalline phases were determined by grazing incidence X-ray diffraction. The curves of current density and voltage showed behaviors characteristic of galvanostatic-potenciostatic grown of anodic oxides, with fluctuations as the result of the spark discharge condition. Micrographs of the oxides showed pores with an average diameter between 60 and 160 nm, which increased at higher voltages. The diffractograms showed the presence of the anatase and rutile phases of TiO2, with a decrease in the anatase fraction at the higher voltages. No influence of surface finishing was observed on the morphology and crystallinity of the coatings. The synthesized oxides show favorable characteristics as potential materials for heterogeneous photocatalytic processes.
DOI: 10.6084/m9.figshare.6857933.v1
title: Porous titanium dioxide coatings synthesized by anodic oxidation

description: ABSTRACT Titanium dioxide is one of the most used materials in heterogeneous photocatalysis due to its commercial availability, low cost, chemical stability, low toxicity and high photocatalytic activity. One of the most efficient and economical methods to obtain TiO2 coatings is the plasma electrolytic oxidation. In this anodization process, a direct current is circulated between a cathode and an anode immersed in an electrolyte solution, at a high voltage that induces the formation of spark discharges on the surface of the anode. In the present work, porous TiO2 coatings were obtained by plasma electrolytic oxidation, using 1 M sulfuric acid as the electrolyte, a Pt cathode, titanium Grade 2 as the anode and a maximum current density of 3250 A m-2. The influence of voltage (90-180 V) and surface finishing (with and without metallographic polishing) on the morphology and crystalline structure was studied. The temporal evolution of voltage and current density were recorded. The morphology of the oxides was observed by scanning electron microscopy, and the crystalline phases were determined by grazing incidence X-ray diffraction. The curves of current density and voltage showed behaviors characteristic of galvanostatic-potenciostatic grown of anodic oxides, with fluctuations as the result of the spark discharge condition. Micrographs of the oxides showed pores with an average diameter between 60 and 160 nm, which increased at higher voltages. The diffractograms showed the presence of the anatase and rutile phases of TiO2, with a decrease in the anatase fraction at the higher voltages. No influence of surface finishing was observed on the morphology and crystallinity of the coatings. The synthesized oxides show favorable characteristics as potential materials for heterogeneous photocatalytic processes.
DOI: 10.6084/m9.figshare.6857930
title: Innovative method of impact testing in high temperatures applied in carbon steels

description: ABSTRACT In this paper, an innovative method of impact tests at high temperature on sub-size Charpy V notched specimens is applied. The innovation lies in the method of heating the specimen, which is performed in situ on a Charpy impact machine type by alternating electrical current through the specimen. The specimens are heated in a few seconds (v=32 ºC/s) and held at the test temperature by an electrical circuit controlled by a thermocouple located on the specimen. Three types of steels are tested; with low, medium and high carbon content (perlitic). The impact energy was measured in the range of ductile fractures, from room temperature to 820 ºC, therefore, for the used steels the range of tested temperature contains the eutectoid phase transformation (AC1) and for the medium carbon steel is includes also has the limiting temperature γ+α / γ (AC3). It is concluded from tests analysis that the impact energy is sensitive to phase transformations. In turn, below AC1 the raise of temperature produced a progressive decrease in the energy absorbed up to a minimum at intermediate temperatures and then up to a maximum prior to phase transformation. Although the initial impetus for the development of this new technology was to estimate the brittle ductile transition that occurs at high temperature for some metal alloys, the wide range of temperatures, high test speed and simplicity of equipment, provides a new research tool for studies at different temperatures, especially on materials having embrittlement activation mechanisms at specific temperature intervals.
DOI: 10.6084/m9.figshare.6857927
title: Droughts and Impacts on Agriculture in the Municipality of Campina Grande - PB

description: Abstract This study aimed to identify and analyze the droughts and its impacts on agriculture in the municipality of Campina Grande - PB. Were used of monthly total data precipitates for the period 1994-2015 of Campina Grande municipality to analyze duration, water deficit and intensity of droughts in this period. To analyze the impacts were used data of agriculture, livestock and agricultural products obtained from the Brazilian Institute of Geography and Statistics. The most severe droughts in the municipality, those with longer durations, water deficits and intensities occurred in the periods of 1997-1999, 2012-2015 and 2001-2003. The permanent crops had greater impact on the quantity produced and average income. Already had temporary acreage reduction, harvested area, amount produced, average yield and production value. The greatest impacts occurred banana, coconut, papaya, bean and corn during 2012 and 2013. There was a reduction of the effective animals during drought, especially in 2012 and 2013. The largest reduction was presented by bovine cattle, goats and sheep. With regard to agricultural products, only decreased the quantity and value of milk production during 2012 and 2014.
DOI: 10.6084/m9.figshare.6857930.v1
title: Innovative method of impact testing in high temperatures applied in carbon steels

description: ABSTRACT In this paper, an innovative method of impact tests at high temperature on sub-size Charpy V notched specimens is applied. The innovation lies in the method of heating the specimen, which is performed in situ on a Charpy impact machine type by alternating electrical current through the specimen. The specimens are heated in a few seconds (v=32 ºC/s) and held at the test temperature by an electrical circuit controlled by a thermocouple located on the specimen. Three types of steels are tested; with low, medium and high carbon content (perlitic). The impact energy was measured in the range of ductile fractures, from room temperature to 820 ºC, therefore, for the used steels the range of tested temperature contains the eutectoid phase transformation (AC1) and for the medium carbon steel is includes also has the limiting temperature γ+α / γ (AC3). It is concluded from tests analysis that the impact energy is sensitive to phase transformations. In turn, below AC1 the raise of temperature produced a progressive decrease in the energy absorbed up to a minimum at intermediate temperatures and then up to a maximum prior to phase transformation. Although the initial impetus for the development of this new technology was to estimate the brittle ductile transition that occurs at high temperature for some metal alloys, the wide range of temperatures, high test speed and simplicity of equipment, provides a new research tool for studies at different temperatures, especially on materials having embrittlement activation mechanisms at specific temperature intervals.
DOI: 10.6084/m9.figshare.6857924
title: Extensión de durabilidad de pistones de bombas de fractura hidráulica mediante el empleo de tecnología de nitruración por plasma y PVD

description: ABSTRACT Hydraulic stimulation technique consists of "fracturing" the formation (rock reservoirs) through pumping a fracturing fluid downhole. This operation is performed by using hydraulic fracturing pumps. The pistons of these pumps are mechanical components performing the intake and compressing fracture fluid by reciprocating action. During this alternative cycle, the entry of fine sand in the gap between piston surface and seals causes localized wear of the piston. Nowadays, commonly used hardening Technology for manufacturing these components is Thermal Spray, which has specific technical weaknesses: chemical and structural inhomogeneity, porosity and lack of adhesion to the substrate due to metallurgical discontinuity between metal base and coating. This paper presents the results obtained by replacing this technique for a new surface treatment using hardening by Plasma Nitriding. The layer obtained has a surface hardness of HV 1100 (Vickers hardness) versus HV 550 achievable with the technique replace, using a DIN 34CrAlNi7 steel as base material. Proposed treatment is supplemented with a second surface hardening treatment by the technique of PVD: Physical Vapor Deposition, which produces a monolayer coating of Al-Cr-N 5µm thick with a final hardness of HV 2500. The hardening treatment described, was used to make a series of plungers for hydraulic fracturing, which were tested in a field technological test, supplemented with standardized laboratory tests on specimens that witnessed the manufacturing process. The plungers manufactured using the new technology proposed by YTEC has a durability which is 313% higher than those of Thermal Spray Technology.
DOI: 10.6084/m9.figshare.6857927.v1
title: Droughts and Impacts on Agriculture in the Municipality of Campina Grande - PB

description: Abstract This study aimed to identify and analyze the droughts and its impacts on agriculture in the municipality of Campina Grande - PB. Were used of monthly total data precipitates for the period 1994-2015 of Campina Grande municipality to analyze duration, water deficit and intensity of droughts in this period. To analyze the impacts were used data of agriculture, livestock and agricultural products obtained from the Brazilian Institute of Geography and Statistics. The most severe droughts in the municipality, those with longer durations, water deficits and intensities occurred in the periods of 1997-1999, 2012-2015 and 2001-2003. The permanent crops had greater impact on the quantity produced and average income. Already had temporary acreage reduction, harvested area, amount produced, average yield and production value. The greatest impacts occurred banana, coconut, papaya, bean and corn during 2012 and 2013. There was a reduction of the effective animals during drought, especially in 2012 and 2013. The largest reduction was presented by bovine cattle, goats and sheep. With regard to agricultural products, only decreased the quantity and value of milk production during 2012 and 2014.
DOI: 10.6084/m9.figshare.6857921
title: Protección de acero para instrumentos quirúrgicos con recubrimientos duros en base carbono tipo DLC

description: ABSTRACT Martensitic stainless steels can be used in different applications such as surgical instruments where a good wear and corrosion resistance are required. Surface modification treatments such as nitriding improve the mechanical properties of these steels, however; they affect the corrosion resistance. For this reason, the DLC (Diamond Like Carbon) coatings deposition can be convenient. The wear and corrosion behaviour was studied in duplex samples (nitrided and PACVD coated) and they were compared with nitrided and only coated samples and with those without treatment, only heat treated (quench and tempering). The coatings were analyzed by Raman spectroscopy and EDS. Pin on disk tests were performed and the adhesion was evaluated using Scratch Test and Rockwell C Indentation. The nanohardness was measured with a Berkovich indenter. The corrosion tests for surgical instruments (according to the Standard ASTM F 1089 -02) and Spray Salt Fog tests were carried out. In the DLC coatings, the ID/IG ratio was 0.8 and the hydrogen content was calculated and resulted to be about 20 %. The coating thickness was 2 µm and the hardness reached 24 GPa. The nitrided layer thickness was 10 µm. The duplex and coated samples presented low friction coefficient and the wear volume loss was undetectable. The coatings had good corrosion behaviour in the corrosion tests. Nevertheless, the nitrided sample presented a corroded region in the copper sulfate and boil tests. The duplex samples had better adhesion than the coated samples in scratch test and indentation Rockwell C.
DOI: 10.6084/m9.figshare.6857924.v1
title: Extensión de durabilidad de pistones de bombas de fractura hidráulica mediante el empleo de tecnología de nitruración por plasma y PVD

description: ABSTRACT Hydraulic stimulation technique consists of "fracturing" the formation (rock reservoirs) through pumping a fracturing fluid downhole. This operation is performed by using hydraulic fracturing pumps. The pistons of these pumps are mechanical components performing the intake and compressing fracture fluid by reciprocating action. During this alternative cycle, the entry of fine sand in the gap between piston surface and seals causes localized wear of the piston. Nowadays, commonly used hardening Technology for manufacturing these components is Thermal Spray, which has specific technical weaknesses: chemical and structural inhomogeneity, porosity and lack of adhesion to the substrate due to metallurgical discontinuity between metal base and coating. This paper presents the results obtained by replacing this technique for a new surface treatment using hardening by Plasma Nitriding. The layer obtained has a surface hardness of HV 1100 (Vickers hardness) versus HV 550 achievable with the technique replace, using a DIN 34CrAlNi7 steel as base material. Proposed treatment is supplemented with a second surface hardening treatment by the technique of PVD: Physical Vapor Deposition, which produces a monolayer coating of Al-Cr-N 5µm thick with a final hardness of HV 2500. The hardening treatment described, was used to make a series of plungers for hydraulic fracturing, which were tested in a field technological test, supplemented with standardized laboratory tests on specimens that witnessed the manufacturing process. The plungers manufactured using the new technology proposed by YTEC has a durability which is 313% higher than those of Thermal Spray Technology.