Nitriding in cathodic cage of stainless steel AISI 316: influence of sample position

R.R.M. de Sousa et al. Nitriding in cathodic cage of stainless steel AISI 316: Influence of sample position. Vacuum, [s.l.], n.83, 2009. Disponivel em: . Acesso em: 04 out.2010.

Nitriding in cathodic cage of stainless steel AISI 316: influence of sample position

R.R.M. de Sousa et al. Nitriding in cathodic cage of stainless steel AISI 316: Influence of sample position. Vacuum, [s.l.], n.83, 2009. Disponivel em: . Acesso em: 04 out.2010.

Estudo das características físico-químicas e biológicas pela adesão de osteoblastos em superfícies de titânio modificadas pela nitretação em plasma

SILVA, J. S. P. Estudo das características físico-químicas e biológicas pela adesão de osteoblastos em superfícies de titânio modificadas pela nitretação em plasma. 2008. 119 f. Tese (Doutorado) - Faculdade de Medicina, Universidade de São Paulo. São Paulo, 2008.

Análise por meio de espectroscopia de emissão óptica das espécies ativas em nitretação iônica e gaiola catódica

Plasma process like ionic nitriding and cathodic cage plasma nitriding are utilized in order to become hard surface of steels. The ionic nitriding is already accepted in the industry while cathodic cage plasma nitriding process is in industrial implementation stage. Those process depend of plasma parameters like electronic and ionic temperature (Te, Ti), species density (ne, ni) and of distribution function of these species. In the present work, the plasma used to those two processes has been observed through Optical Emission Spectroscopy OES technique in order to identify presents species in the treatment ambient and relatively quantify them. So plasma of typical mixtures like N2 H2 has been monitored through in order to study evolution of those species during the process. Moreover, it has been realized a systematic study about leaks, also thought OES, that accomplish the evolution of contaminant species arising because there is flux of atmosphere to inside nitriding chamber and in what conditions the species are sufficiently reduced. Finally, to describe the physic mechanism that acts on both coating techniques ionic nitriding and cathodic cage plasma nitriding

Avaliação do desempenho do aço D6 tratado termicamente e netretado em plasma com gaiola catódica visando aplicação industrial

In this research there was an evaluation of the best conditions of nitriding in plasma within a cathodic cage at an atmosphere of 80% N2-20%H2 in samples of tool manganese steel AISI D6, cold working, treated thermally in the following conditions: tension relief, treated thermally to temperature of maximum heat, temperate heat and temperate and temperate heat. A pressure of 2.5mbar and temperatures of 400 and 300ºC com treatment time of two and three hours were used to evaluate its performance as cutting tool (punch) of bicycle backs. Hardness, micro-structural aspects (layer thickness, interface, grain size etc), and crystal phases on the surface were appraised. When treated to tension relief, thermally treated to maximum heat temperature, temperature and temperate heat, the samples presented hardness levels of 243HV, 231HV, 832HV, and 653HV, respectively. The best nitrification conditions were: four hours and 300ºC for heat samples. A superficial hardness of 1000HV and a 108µm thickness for the nitrided layer were found in these samples

Avaliação do desempenho do aço AISI D2 tratado termicamente e nitretado em plasma com gaiola catódica visando aplicação industrial

In the research, steel samples tool AISI D2, treated thermally, in the conditions: relief of tension, when maximum, seasoned and seasoned was treated thermally in the temperature of revenimento and revenida had been nitrited in plasma with cathodic cage, in atmosphere of 80%N2:20%H2. One used pressure of 2,5 mbar, 400 and 480°C temperatures with treatment time of 3 and 4 hours, with the objective to evaluate its performance in pipes cut tool. It was compared that the performance of the same steel when only thermally treated, both with tension relief. It was evaluated its hardness. Microstructural aspects (the layer thickness, interface, graisn size, etc) and crystalline phases on the surface. Besides, it was verified accomplishment possibility of nitriding simultaneous to annealing treatment. The tempering samples had presented hardness levels of 600 HV, while in nitrited samples these values had been 1100 HV

Nitretação em plasma com gaiola catódica: investigação do mecanismo e estudo comparativo com a nitretação em plasma de tensão contínua

The ionic plasma nitriding is one of the most important plasma assisted treatment technique for surface modification, but it presents some inherent problems mainly in nitriding pieces with complex geometries. In the last four years has appeared a plasma nitriding technique, named ASPN (Active Screen Plasma Nitriding) in which the samples and the workload are surrounded by a metal screen on which the cathodic potential is applied. This new technique makes possible to obtain a perfect uniform nitrided layer apart from the shape of the samples. The present work is based on the development of a new nitriding plasma technique named CCPN (Cathodic Cage Plasma Nitriding) Patent PI 0603213-3 derived from ASPN, but utilizes the hollow cathode effect to increase the nitriding process efficiency. That technique has shown great improvement on the treatment of several types of steels under different process conditions, producing thicker and harder layers when compared with both, ASPN and ionic plasma nitriding, besides eliminating problems associated with the later technique. The best obtained results are due to the hollow cathode effect on the cage holes. Moreover, characteristic problems of ionic plasma nitriding are eliminated due to the fact that the luminescent discharge acts on the cage wall instead of on the samples surface, which remains under a floating potential. In this work the enhancement of the cathodic cage nitriding layers proprieties, under several conditions for some types of steels was investigated, besides the mechanism for nitrides deposition on glass substrate, concluding that the CCPN is both a diffusion and a deposition process at the same time

Influência dos parâmetros de processo na deposição de nitreto de titânio por plasma em gaiola catódica

Titanium nitride films were grown on glass using the Cathodic Cage Plasma Deposition technique in order to verify the influence of process parameters in optical and structural properties of the films. The plasma atmosphere used was a mixture of Ar, N2 and H2, setting the Ar and N2 gas flows at 4 and 3 sccm, respectively and H2 gas flow varied from 0, 1 to 2 sccm. The deposition process was monitored by Optical Emission Spectroscopy (OES) to investigate the influence of the active species in plasma. It was observed that increasing the H2 gas flow into the plasma the luminescent intensities associated to the species changed. In this case, the luminescence of N2 (391,4nm) species was not proportional to the increasing of the H2 gas into the reactor. Other parameters investigated were diameter and number of holes in the cage. The analysis by Grazing Incidence X-Ray Diffraction (GIXRD) confirmed that the obtained films are composed by TiN and they may have variations in the nitrogen amount into the crystal and in the crystallite size. The optical microscopy images provided information about the homogeneity of the films. The atomic force microscopy (AFM) results revealed some microstructural characteristics and surface roughness. The thickness was measured by ellipsometry. The optical properties such as transmittance and reflectance (they were measured by spectrophotometry) are very sensitive to changes in the crystal lattice of the material, chemical composition and film thicknesses. Therefore, such properties are appropriate tools for verification of this process control. In general, films obtained at 0 sccm of H2 gas flow present a higher transmittance. It can be attributed to the smaller crystalline size due to a higher amount of nitrogen in the TiN lattice. The films obtained at 1 and 2 sccm of H2 gas flow have a golden appearance and XRD pattern showed peaks characteristics of TiN with higher intensity and smaller FWHM (Full Width at Half Maximum) parameter. It suggests that the hydrogen presence in the plasma makes the films more stoichiometric and becomes it more crystalline. It was observed that with higher number of holes in the lid of the cage, close to the region between the lid and the sample and the smaller diameter of the hole, the deposited film is thicker, which is justified by the most probability of plasma species reach effectively the sample and it promotes the growth of the film

Estudo da viabilidade técnica para obtenção de superfície duplex em aço inoxidável martensítico AISI 410 através do processo de deposição a plasma por gaiola catódica

The technique of plasma nitriding by the cathode cage mainly stands out for its ability to produce uniform layers, even on parts with complex geometries. In this study, it was investigated the efficiency of this technique for obtaining duplex surface, when used, simultaneously, to nitriding treatment and thin film deposition at temperatures below 500°C. For this, were used samples of AISI 41 0 Martensitic Stainless Steel and performed plasma treatment, combining nitriding and deposition of thin films of Ti and/or TiN in a plasma atmosphere containing N2-H2. It was used a cathodic cage of titanium pure grade II, cylindrical with 70 mm diameter and 34 mm height. Samples were treated at temperature 420ºC for 2 and 12 hours in different working pressures. Optical Microscopy (OM), Scanning Electron Microscopy (SEM) with micro-analysis by Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) and analysis of Vickers Microhardness were used to investigate coating properties such as homogeneity and surface topography, chemical composition, layer thickness, crystalline phase, roughness and surface microhardness. The results showed there is a direct proportionality between the presence of H2 in plasma atmosphere and the quantity of titanium in surface chemical composition. It was also observed that the plasma treatment at lowpressure is more effective in formation of TiN thin film

Nitretação iônica sem efeito de borda :desenvolvimento e avaliação de uma nova técnica

The ionic nitriding process presents some limitations related with the control of the thickness of the layer and its uniformity. Those limitations that happen during the process, are produced due to edge effects, damage caused by arcing arc and hollow cathode, mainly in pieces with complex geometry and under pressures in excess of 1 mbar. A new technique, denominated ASPN (active screen shapes nitriding) it has been used as alternative, for offering many advantages with respect to dc plasma conventional. The developed system presents a configuration in that the samples treated are surrounded by a large metal screen at high voltage cathodic potencials, (varying between 0 and 1200V) and currents up to 1 A. The sample is placed in floting potential or polarized at relatively lower bias voltages by an auxiliary source. As the plasma is not formed directly in the sample surface but in the metal screen, the mentioned effects are eliminated. This mechanism allows investigate ion of the transfer of nitrogen to the substrate. Optical and electronic microscopy are used to exam morphology and structure at the layer. X-ray difration for phase identification and microhardness to evaluate the efficiency of this process with respect to dc conventional nitriding

Nitretação em plasma com gaiola catódica: caracterização e avaliação do desempenho da camada nitretada em facas de corte

Nowadays, in the plastic industry are used mills that accomplish the recycling of residues generated in the production of its components. These mills contain cut sheets that suffer accelerated wear, once they are submitted constantly to the tribologic efforts, decreasing its useful life. To reduce this problem, it s used noble steels or takes place superficial treatments. The ionic nitriding process presents some limitations related to the uniformity of the layer in pieces with complex geometry, committing its application in pieces as knives, head offices, engagements, etc. However, the new technique of nitriding in cathodic cage eliminates some problems, as the restrictions rings, inherent to the conventional ionic nitriding. In present work, was studied the use viabilization of steels less noble, as SAE 1020, SAE 4320 and SAE 4340, nitreded by two different techniques, to substitute the AISI 01 steels, usually used in the cut knifes fabrication, seeking to reduce the costs and at the sane time to increase the useful life of these knifes. The steel most viable was the SAE 4340, nitrided in cathodic cage, because it presented uniformity in thickness and in the hardness of the layer, besides of increased 58% in the average its useful life

Desenvolvimento e teste de um protótipo de reator de plasma com gaiola catódica rotatória para nitretação em lote de pequenas peças

The technique of ion nitriding, despite being fully consolidated in the industry, has great limitations when applied to the treatment of small parts. This is because effects that occur due to non-uniformity of the electric field, generate localized heating in parts, damaging the uniformity of nitrided layer. In addition, because the samples are treated static parts thereof are untreated. To expand the use of plasma nitriding, this work presents the development, assembly and testing of a prototype plasma reactor with rotatory cathodic cage [patent pending], able to meet these needs, giving the material a uniform treatment and opening doors to industrial scale production. The samples tested with hexagonal nuts are 6.0 mm in diameter, made of stainless steel AISI 304 nitrided at a pressure of 1 mbar in an atmosphere of 20% H2 + 80% N2 for 1 h. After treatment, testing visual inspection, optical microscopy and microhardness were carried out to check the effectiveness of the process for uniformity and hardness of the parts. All samples exhibited uniform color, and matte brownish, unlike the untreated samples, silver color and gloss. The hardness of the surface (top and sides) was 65% and even higher than the original hardness. The nitrided layer showed great uniformity in microstructure and thickness. It is concluded, therefore, that the unit was effective constructed for the purposes for which it was designed

Caracterização magnética e estrutural de filmes depositados por gaiola catódica

Iron nitrite films, with hundred of nanometers thick, were deposited using the Cathodic cage plasma nitriding method, with a N2/H2 plasma, over a common glass substract. The structure, surface morphology and magnetic properties were investigated using X-ray diffractometry (XRD), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM). XRD shows the formation of γ FeN phase and a combination of ζFe2N + ɛFe3N phases. The film s saturation magnetization and coercivity depends on morphology, composition, grain size and treatment temperature. Temperature raising from 250 ºC to 350 ºC were followed by an increase in saturation magnetization and film s surface coercivity on the parallel direction in relative proportion. This fact can be attributed to the grain sizes and to the different phases formed, since iron rich fases, like the ɛFe3N phase, emerges more frequently on more elevated treatment s temperature. Using this new and reasonably low cost method, it was possible to deposit films with both good adhesion and good magnetic properties, with wide application in magnetic devices

Adesão de células mesenquimais da medula óssea de camundongos e do ligamento periodontal de ratos a diferentes superfícies de titânio: estudo comparativo in vitro

The present experiment used cell culture to analyze the adhesion capacity of mouse mesenchymal bone marrow cells and rat periodontal ligament to different titanium surfaces. Grade II ASTM F86 titanium discs 15mm in diameter and 1.5mm thick were used and received 2 distinct surface treatments (polished and cathodic cage plasma nitriding). The cells were isolated from the mouse bone marrow and rat periodontal ligament and cultured in α-MEM basic culture medium containing antibiotics and supplemented with 10% FBS and 5% CO2, for 72 hours at 37ºC in a humidified atmosphere. Subculture cells were cultured in a 24-well plate with a density of 1 x 104 cells per well. The titanium discs were distributed in accordance with the groups, including positive controls without titanium discs. After a 24-hour culture, the cells were counted in a Neubauer chamber. The results show that both the mouse mesenchymal bone marrow cells and rat periodontal ligament cells had better adhesion to the control surface. The number of bone marrow cells adhered to the polished Ti surface was not statistically significant when compared to the same type of cell adhered to the Ti surface treated by cathodic cage plasma nitriding. However a significant difference was found between the control and polished Ti groups. In relation to periodontal ligament cell adhesion, a significant difference was only found between the control and plasma-treated Ti surfaces. When comparing equal surfaces with different cells, no statistically significant difference was observed. We can therefore conclude that titanium is a good material for mesenchymal cell adhesion and that different material surface treatments can influence this process

Avaliação in vitro da adesão e proliferação de células mesenquimais do ligamento periodontal humano em diferentes superfícies de titânio

In the last years, many scientific researches in implantology have been focused on alternatives that would provide higher speed and quality in the process of osseointegration. Different treatment methods can be used to modify the topographic and chemical properties of titanium surface in order to optimize the tissue-implant reactions by a positive tissue response. This study aimed to evaluate the adhesion and proliferation of mesenchymal cells from human periodontal ligament on two different titanium surfaces, using cell culture techniques. Grade II titanium discs received different surface treatments, forming two distinct groups: polished and cathodic cage plasma nitriding. Human periodontal ligament mesenchymal cells were cultured on titanium discs in 24-well cell culture plates, at a density of 2 x 104 cells per well, including wells with no discs as positive control. Data obtained by counting the cells that adhered to the titanium surfaces (polished group and cathodic cage group) and to the plastic surface (control group), in the 24, 48 and 72-hour periods after plating, were used to analyze cell adhesion and proliferation and to obtain the cell growing curve in the different groups. The data were submitted to nonparametric analysis and the differences between groups were compared by Kruskal-Wallis and Friedman statistical tests. No statistically significant differences were found in the cells counts between the groups (p>0.05). It was concluded that both treatments produced surfaces compatible with the adhesion and proliferation of human periodontal ligament mesenchymal cells