Microstructural and XRD analysis and study of the properties of the system Ti-TiAl-B4C processed under different operational conditions

High specific modulus materials are considered excellent for the aerospace industry. The system Ti-TiAl-B4C is presented herein as an alternative material. Secondary phases formed in situ during fabrication vary depending on the processing conditions and composition of the starting materials. The final behaviors of these materials are therefore difficult to predict. This research focuses on the study of the system Ti-TiAl-B4C, whereby relations between microstructure and properties can be predicted in terms of the processing parameters of the titanium matrix composites (TMCs). The powder metallurgy technique employed to fabricate the TMCs was that of inductive hot pressing (iHP) since it offers versatility and flexibility. The short processing time employed (5 min) was set in order to test the temperature as a major factor of influence in the secondary reactions. The pressure was also varied. In order to perform this research, not only were X-Ray Diffraction (XRD) analyses performed, but also microstructural characterization through Scanning Electron Microscopy (SEM). Significant results showed that there was an inflection temperature from which the trend to form secondary compounds depended on the starting material used. Hence, the addition of TiAl as an elementary blend or as prealloyed powder played a significant role in the final behavior of the TMCs fabricated, where the prealloyed TiAl provides a better precursor of the formation of the reinforcement phases from 1100 °C regardless of the pressur

Study protocol - efficacy of an attachment-based working alliance in the multimodal pain treatment

Background: The concept of attachment is relevant for the onset and development of chronic pain. Insecure attachment styles negatively affect therapeutic outcome. Insecurely attached patients seem to be less able to sustain positive effects of a multimodal treatment program. However, it has never been tested before if an attachment-oriented approach can improve treatment results of insecurely attached patients in a multimodal outpatient setting. To test this assumption, we compare the short- and long-term outcomes for pain patients who will receive multidisciplinary, attachment-oriented treatment with the outcomes for patients in a control group, who will receive the multidisciplinary state-of-the-art treatment. Methods: Two patient groups (baseline, attachment intervention) are assessed before treatment, after treatment, and at a 6 month follow-up. The study is conducted in a block design: After data collection of the first block (controls) and before as well as during data collection for the second block (treatment group), the health care personnel of the outpatient pain clinic receives training on attachment theory and its use in the therapeutic context. Pain intensity as measured with visual analogue scales and physical functioning will serve as the primary outcome measures. Discussion: The design of our study allows for a continuous exchange of experienced team members, which may help bring about concrete attachment related guidelines for the enhancement of therapeutic outcome. This would be the first attempt at an attachment-oriented improvement of multimodal pain programs. Conclusion: An attachment-based approach may be a promising way to enhance long-term treatment outcomes for insecurely attached pain patients. Trial registration: DRKS00008715 (registered on the 3rd of June 2015)

Estudio comparativo del comportamiento de diversos materiales de refuerzo en matrices de titanio fabricados mediante compactación por sinterización rápida

Regarding titanium matrix composites (TMCs), their properties strongly depend on the reinforcement material employed for their manufacturing; this may lead to a multitude of investigations on TMCs. Considering the diverse typology of the reinforcement, six types of ceramic particles were tested in this investigation: B₄C, SiB₆ , TiB₂ , TiC, TiN, and BN. In order to compare their behaviour and their own influence on the properties of the TMCs, the same ratio was employed in the starting materials, 30% volume. Among the techniques for developing TMCs, a significant number of authors propose Powder Metallurgy as a favourable route. In this framework, the novel Rapid Sinter Pressing technique was employed to perform the present study, due to its flexibility, repeatability, and reproducibility, as well as short-run cycle times. The processing temperature (930 °C) was set with the intention of evaluating how the reinforcements behave differently depending on their reactivity with the Ti matrix. In this regard, the main objective of the research was to carry out a comparison on the behaviour of seven TMCs fabricated with similar operational parameters via RSP.En cuanto a los materiales compuestos de base titanio (TMC), sus propiedades dependen en gran medida del material de refuerzo empleado para su fabricación; dando lugar a una gran diversidad de investigaciones sobre los TMCs. Considerando la diversa tipología del refuerzo, en este estudio se trabajó con seis tipos de partículas cerámicas: B₄C, SiB₆,TiB₂ , TiC, TiN y BN. Para poder comparar su comportamiento e influencia sobre las propiedades de los TMCs, se empleó siempre la misma proporción con respecto al material de partida, 30% en volumen. Entre las técnicas que se conocen para desarrollar TMCs, la pulvimetalurgia ha sido propuesta como una vía favorable por un número significativo de autores. En este marco, para la realización del presente estudio, se utilizó la novedosa técnica Rapid Sinter Pressing, debido a su flexibilidad, repetibilidad y reproducibilidad, así como a sus reducidos tiempos de ciclo. La temperatura de procesamiento (930 °C) se estableció con la intención de evaluar cómo los refuerzos afectan de diferente manera, en función de su reactividad con la matriz de Ti. En este sentido, el objetivo principal de esta investigación ha sido realizar una comparativa del comportamiento de siete TMCs fabricados vía de Compactación por Sinterización Rápida (Rapid Sinter Pressing) bajo las mismas condiciones de procesado.Universidad de Sevilla VI PPIT-2020-I.

Study of the Influence of TiB Content and Temperature in the Properties of In Situ Titanium Matrix Composites

This work focuses on the study of the microstructure, hardening, and stiffening effect caused by the secondary phases formed in titanium matrices. These secondary phases originated from reactions between the matrix and boron particles added in the starting mixtures of the composites. Not only was the composite composition studied as an influencing factor in the behaviour of the composites, but also different operational temperatures. Three volume percentages of boron content were tested (0.9 vol %, 2.5 vol %, and 5 vol % of amorphous boron). The manufacturing process used to produce the composites was inductive hot pressing, which operational temperatures were between 1000 and 1300º C. Specimens showed optimal densification. Moreover, microstructural studies revealed the formation of TiB in various shapes and proportions. Mechanical testing confirmed that the secondary phases had a positive influence on properties of the composites. In general, adding boron particles increased the hardness and stiffness of the composites; however rising temperatures resulted in greater increases in stiffness than in hardnes

Analysis of the Influence of Starting Materials and Processing Conditions on the Properties of W/Cu Alloys

In this work, a study of the influence of the starting materials and the processing time used to developW/Cu alloys is carried out. Regarding powder metallurgy as a promising fabrication route, the difficulties in producingW/Cu alloys motivated us to investigate the influential factors on the final properties of the most industrially demanding alloys: 85-W/15-Cu, 80-W/20-Cu, and 75-W/25-Cu alloys. Two different tungsten powders with large variation among their particle size—fine (Wf) and coarse (Wc) powders—were used for the preparation ofW/Cu alloys. Three weight ratios of fine and coarse (Wf:Wc) tungsten particles were analyzed. These powders were labelled as “tungsten bimodal powders”. The powder blends were consolidated by rapid sinter pressing (RSP) at 900 C and 150MPa, and were thus sintered and compacted simultaneously. The elemental powders andW/Cu alloys were studied by optical microscopy (OM) and scanning electron microscopy (SEM). Thermal conductivity, hardness, and densification were measured. Results showed that the synthesis ofW/Cu using bimodal tungsten powders significantly affects the final alloy properties. The higher the tungsten content, the more noticeable the effect of the bimodal powder. The best bimodalWpowder was the blend with 10 wt % of fine tungsten particles (10-Wf:90-Wc). These specimens present good values of densification and hardness, and higher values of thermal conductivity than other bimodal mixtures.Junta de Andalucía TIC-752

High cell density cultivation and recombinant protein production with Escherichia coli in a rocking-motion-type bioreactor

<p>Abstract</p> <p>Background</p> <p>Single-use rocking-motion-type bag bioreactors provide advantages compared to standard stirred tank bioreactors by decreased contamination risks, reduction of cleaning and sterilization time, lower investment costs, and simple and cheaper validation. Currently, they are widely used for cell cultures although their use for small and medium scale production of recombinant proteins with microbial hosts might be very attractive. However, the utilization of rocking- or wave-induced motion-type bioreactors for fast growing aerobic microbes is limited because of their lower oxygen mass transfer rate. A conventional approach to reduce the oxygen demand of a culture is the fed-batch technology. New developments, such as the BIOSTAT^®CultiBag RM system pave the way for applying advanced fed-batch control strategies also in rocking-motion-type bioreactors. Alternatively, internal substrate delivery systems such as EnBase^®Flo provide an opportunity for adopting simple to use fed-batch-type strategies to shaken cultures. Here, we investigate the possibilities which both strategies offer in view of high cell density cultivation of <it>E. coli </it>and recombinant protein production.</p> <p>Results</p> <p>Cultivation of <it>E. coli </it>in the BIOSTAT^®CultiBag RM system in a conventional batch mode without control yielded an optical density (OD₆₀₀) of 3 to 4 which is comparable to shake flasks. The culture runs into oxygen limitation. In a glucose limited fed-batch culture with an exponential feed and oxygen pulsing, the culture grew fully aerobically to an OD₆₀₀of 60 (20 g L^-1cell dry weight). By the use of an internal controlled glucose delivery system, EnBase^®Flo, OD₆₀₀of 30 (10 g L^-1cell dry weight) is obtained without the demand of computer controlled external nutrient supply. EnBase^®Flo also worked well in the CultiBag RM system with a recombinant <it>E. coli </it>RB791 strain expressing a heterologous alcohol dehydrogenase (ADH) to very high levels, indicating that the enzyme based feed supply strategy functions well for recombinant protein production also in a rocking-motion-type bioreactor.</p> <p>Conclusions</p> <p>Rocking-motion-type bioreactors may provide an interesting alternative to standard cultivation in bioreactors for cultivation of bacteria and recombinant protein production. The BIOSTAT^®Cultibag RM system with the single-use sensors and advanced control system paves the way for the fed-batch technology also to rocking-motion-type bioreactors. It is possible to reach cell densities which are far above shake flasks and typical for stirred tank reactors with the improved oxygen transfer rate. For more simple applications the EnBase^®Flo method offers an easy and robust solution for rocking-motion-systems which do not have such advanced control possibilities.</p

Processing by Additive Manufacturing Based on Plasma Transferred Arc of Hastelloy in Air and Argon Atmosphere

This research was carried out to determinate the effect of the atmosphere processing conditions (air and argon) and two specific thermal treatments, on the properties of specimens made from the nickel-based alloy Hastelloy C-22 by plasma transferred arc (PTA). Firstly, the additive manufacturing parameters were optimized. Following, two walls were manufactured in air and argon respectively. Afterwards, a determinate number of specimens were cut out and evaluated. Regarding the comparison performed with the extracted specimens from both walls, three specimens of each wall were studied as-built samples. Furthermore, a commonly used heat treatment in Hastelloy, with two different cooling methods, was selected to carry out additional comparisons. In this respect, six additional specimens of each wall were selected to be heat treated to a temperature of 1120 °C for 20 min. After the heat treatment, three of them were cooled down by rapid air cooling (RAC), while the other three were cooled down by water quenching (WQ). In order to study the influence degree of the processing conditions, and how the thermal treatments could modify the final properties of the produced specimens, a detailed characterization was performed. X-ray diffraction and microstructural analyses revealed the phases-presence and the apparition of precipitates, varying the thermal treatment. Moreover, the results obtained after measuring mechanical and tribological properties showed slight changes caused by the variation of the processing atmosphere. The yield strength of the extracted specimens from the two walls achieved values closer to the standards ones in air 332.32 MPa (±21.36 MPa) and in argon 338.14 MPa (±9 MPa), both without thermal treatment. However, the effect of the cooling rate resulted as less beneficial, as expected, reducing the deformation properties of the specimens below 11%, independently of the air or argon manufacturing atmosphere and the cooling rate procedure.Universidad de Sevilla (España) PPIT-2018-I.

Effect of processing atmosphere and secondary operations on the mechanical properties of additive manufactured AISI 316L stainless steel by Plasma Metal Deposition

Plasma metal deposition (PMD) is an interesting additive technique whereby diverse materials can be employed to produce end parts with complex geometries. This study investigates not only the effects of the manufacturing conditions on the final properties of 316L stainless steel specimens by PMD, but it also affords an opportunity to study how secondary treatments could modify these properties. The tested processing condition was the atmosphere, either air or argon, with the other parameters having previously been optimized. Furthermore, two standard thermal treatments were conducted with the intention of broadening knowledge regarding how these secondary operations could cause changes in the microstructure and properties of 316L parts. To better appreciate and understand the variation of conditions affecting the behavior properties, a thorough characterization of the specimens was carried out. The results indicate that the presence of vermicular ferrite (δ) varied slightly as a consequence of the processing conditions, since it was less prone to appear in specimens manufactured in argon than in air. In this respect, their mechanical properties suffered variations; the higher the ferrite (δ) content, the higher the mechanical properties measured. The degree of influence of the thermal treatment was similar regardless of the processing conditions, which affected the properties based on the heating temperature.European Union Horizon 2020 Program (H2020) grant agreement no 768612Universidad de Sevilla (España) VI PPIT-2019-I.

Analysis of the microstructure and mechanical properties of Titanium-based composites reinforced by secondary phases and B4C particles produced via direct hot pressing

In the last decade, titanium metal matrix composites (TMCs) have received considerable attention thanks to their interesting properties as a consequence of the clear interface between the matrix and the reinforcing phases formed. In this work, TMCs with 30 vol % of B4C are consolidated by hot pressing. This technique is a powder metallurgy rapid process. Incorporation of the intermetallic to the matrix, 20 vol % (Ti-Al), is also evaluated. Here, the reinforcing phases formed by the reaction between the titanium matrix and the ceramic particles, as well as the intermetallic addition, promote substantial variations to the microstructure and to the properties of the fabricated composites. The influences of the starting materials and the consolidation temperature (900 C and 1000 C) are investigated. By X-ray diffraction, scanning and transmission electron microscopy analysis, the in-situ-formed phases in the matrix and the residual ceramic particles were studied. Furthermore, mechanical properties are studied through tensile and bending tests in addition to other properties, such as Young’s modulus, hardness, and densification of the composites. The results show the significant effect of temperature on the microstructure and on the mechanical properties from the same starting powder. Moreover, the Ti-Al addition causes variation in the interface between the reinforcement and the matrix, thereby affecting the behaviour of the TMCs produced at the same temperature.Junta de Andalucía TIC-752