The usage of titanium alloys in many industries has increased significantly over the years due to their superior properties. However, they are extremely difficult to machine because of their distinctive characteristics such as their high temperature strength, low thermal conductivity, and high chemical affinity for tool materials. Hence, despite their increased usage, they are still expensive to machine when compared to other metals. The current research aims to address the machinability issues of titanium alloys by developing novel compositions of a new generation of self-adaptive Physical Vapor Deposition (PVD) coatings that function by forming beneficial tribo-films through their interaction with the environment. These tribo-films form during cutting and provide enhanced lubricity, hardness, strength, and thermal barrier characteristics to the cutting tool. It was found that during Ti6Al4V machining, significant BUE and crater wear formation occurs; however, one is dominant over the other depending on the cutting conditions. Therefore, the coatings investigated were designed by taking into consideration the dominant tool wear mechanisms and the complex tribological phenomena that occur in the cutting zone. The current research investigated monolayer TiB2 and CrN self-adaptive PVD coatings for the rough (cutting speed - 45 m/min, feed -0.15 mm/rev, and depth of cut – 2 mm) and finish (cutting speed - 150 m/min, feed -0.1225 mm/rev, and depth of cut – 0.25 mm) turning of Ti6Al4V alloy. Detailed experimental studies were performed to study the effectiveness of the coatings during machining. Micro-mechanical characteristics of the coatings were also studied to understand how coating properties affect the coatings performance in machining and tribo-film formation. The results obtained show that both the TiB2 and CrN coatings significantly improve tool performance during the rough turning of Ti6Al4V alloy compared to the current industrial standard, which is due to certain micro-mechanical coating properties and the beneficial tribo-films formed. A coating of CrN coating was found to increase tool life during finish turning. It was also established that for machining applications where intensive adhesive interaction occurs at the tool-chip interface, coatings with lower hardness values perform significantly better than harder ones. / Thesis / Doctor of Philosophy (PhD) / Titanium alloys are increasingly becoming the material of choice for many industrial applications due to their superior properties. However, they are very difficult to machine since they have high chemical affinity towards tool materials, low thermal conductivity, and high temperature strength. These properties cause rapid failure of the tool. The objective of the current research is to address machinability issues during Ti6Al4V machining and improve tool performance. One effective strategy to minimize tool wear is to apply self-adaptive PVD tool coatings that can form beneficial tribo-films through their interaction with the environment and provide enhanced lubricity, hardness, strength, and thermal barrier characteristics to the cutting tool. In the current research, two self-adaptive PVD coatings were developed that offset the dominant tool wear mechanisms prevalent during the rough and finish turning of Ti6Al4V alloy and reduced the tool wear rate by more than 60% compared to the current industrial standard.

En av de mest oönskade bieffekterna vid metallbearbetning är att det blidas grader. Grader kan definieras som plastiskt deformerat material som bildas på en produkts kanter och hörn. De uppstår oftast vid skär- och skjuvande operationer och kan bero på många olika faktorer. Verktygshastighet, skärpa på verktyget och materialvariationer för att nämna några. Dessa grader kan påverka en produkts egenskaper negativt i många avseenden. Att avlägsna dessa grader är både kostsamt, tidskrävande och ett slitsamt monotont arbete. Side Systems AB i Oviken tillverkar ventilblock i aluminium 2007/2033, Automatstål 11SMnPb30 och Segjärn 500–7 och lägger i dagsläget stora resurser på att avlägsna grader. Därför finns en efterfrågan från företaget i att minska denna kostnad och undersöka om det med en vakuumgradningsmaskin EDS-900 går att avlägsna grader på ett effektivt sätt. En bieffekt av vakuumgradning kan vara att Ra-värdet förändras. I detta projekt undersöktes hur olika medier (granulat) hanterade uppgiften att avlägsna grader och hur de förändrade ytjämnheten. Detta utfördes genom mätningar av Ra före och efter gradningsprocessen och genom visuell undersökning av grader i färdigbehandlade produkter. Detta gjordes på ett urval av olika medier och material för att påvisa hur de faktorerna påverkar den slutgiltiga produkten och dess ytjämnhet. Denna undersökning visade att granulat med glaskulor med storlek 90–150 μm påverkade ytjämnheten för aluminium 2007, Automatstål 11SMnPb30 så att Ra-värdet låg under det av Side Systems ställda gränsvärde på 1,6. För segjärn 500–7 uppfyllde inga granulat de ställda kraven. Resultatet av denna undersökning visar även att granulat med glaskulor och storleken 90–150 µm avlägsnar grader på ventilblock tillverkade i aluminium 2007. För resultat på automatstål 11SMnPb30 och segjärn 500–7 behövs vidare studier. Som slutsats kan arbetet användas som underlag för inköp. / One of the most undesirable side effects in metal processing is the formation of burrs. Burrs can be defined as plastic deformations that occur on the edges and corners of a product. They are most commonly generated during cutting and shearing operations and can be attributed to various factors, such as tool speed, sharpness, and material variations, among others. These burrs can have negative implications on the properties of a product in multiple ways. The removal of these burrs is both costly and time-consuming, requiring tedious and labor-intensive work. Side Systems AB in Oviken manufactures valve blocks using Aluminum 2007/2033, Automaton Steel 11SMnPb30, and Cast Iron 500–7 and currently invests significant resources in burr removal. Therefore, there is a request from the company to reduce this cost and investigate whether it is possible to effectively remove burrs using a vacuum deburring machine EDS-900. One side effect of vacuum deburring may be a change in the Ra value. This project aimed to examine how different media (granules) handled the task of removing burrs and how they affected the surface finish. This was achieved through measurements of Ra before and after the deburring process and through visual inspection of burrs in finished products. This was carried out on a selection of different media and materials to demonstrate how these factors impact the final product and its surface finish. This study revealed that granules with glass beads sized 90–150 μm had an impact on the surface smoothness of Aluminum 2007 and Automaton Steel 11SMnPb30, resulting in Ra values below the threshold set by Side Systems at 1.6. For Cast Iron 500–7, none of the tested granules met the specified requirements. However, it should be noted that the aforementioned granules were not examined specifically on cast Iron in this study. This investigation demonstrated that granules with glass beads sized 90–150 µm affected the surface smoothness of Aluminum 2007 and Automaton Steel 11SMnPb30, resulting in Ra values below the specified threshold of 1.6 set by Side Systems. However, none of the tested granules met the requirements for Cast Iron 500–7. The results of this investigation also indicated that granules with glass beads, sized 90–150 µm, effectively remove burrs on valve blocks manufactured in Aluminum 2007. Further studies are required to assess the results for Automaton Steel 11SMnPb30 and Cast Iron 500–7. The conclusion of the work can be used as a basis for procurement. / <p>Betygsdatum 2023-06-28</p>

Various nitrides, such as chromium nitride and titanium nitride, find extensive use in cutting tools, micromechanical devices, and medical implants due to their exceptional physical, mechanical, and chemical properties. These coatings exhibit superior hardness compared to high-speed steel and cemented carbide along with notable protective capabilities against corrosion and wear. These coatings have been successfully used to enhance the properties of cemented carbide and steel tools while safeguarding their surfaces. By adjusting deposition parameters like N2 gas pressure, the properties of PVD coatings can be tailored to effectively withstand specific dominant wear modes during machining. The study investigates and demonstrates that CrN coatings can be specifically engineered to have distinct mechanical and tribological properties by adjusting the N2 gas pressure, which enhances machining performance in cases where BUE formation occurs. A comprehensive coating characterization was conducted for each CrN coating studied. Wear performance assessments of the various CrN-coated WC tools were carried out during dry finish turning of SS 304. Additionally, high temperature coating characterization was performed for the best-performing in house deposited coating (nitrogen gas pressure of 4 Pa, bias voltage of -50 V) and a commercial coating, up to 450°C. The results highlighted the influence of N2 gas pressure on the structural, mechanical, and tribological properties of CrN coatings. The findings indicate that coatings with a comparatively low H/E ratio (while maintaining higher elastic modulus values), low roughness, moderate residual stress, high plasticity index, and high toughness exhibited superior performance when machining sticky materials and in high-temperature applications prone to adhesive wear and built-up edge (BUE) formation. Furthermore, high-temperature studies confirmed that the in-house coating retained a low H/E ratio, high plasticity index, high toughness, and low roughness, without compromising the hardness or elastic modulus values. In contrast, the commercial coating failed to retain its properties at higher temperatures. These high-temperature studies provide valuable insights for selecting CrN coatings tailored for machining materials that tend to adhere to the cutting tool and for high-temperature applications. / Dissertation / Master of Applied Science (MASc) / Coating properties such as hardness, residual stress, adhesive behaviour, elastic modulus, and roughness significantly affect tool performance and wear patterns, besides machining parameters and conditions. This research focuses on CrN coatings deposited by PVD cathodic arc deposition, adjusting the N2 gas pressure while keeping bias voltage constant. The research investigates and illustrates that CrN coatings can be specifically tailored (by adjusting the N2 gas pressure) to possess unique mechanical, and tribological properties that ameliorate machining performance in scenarios involving BUE formation. Three CrN coatings were deposited using the PVD technique by varying the N2 gas pressure. A thorough coating characterization was conducted for each of three in house deposited coatings and one commercially available coating. The wear behaviour of different CrN-coated WC tools was evaluated during dry finish turning of SS 304 to identify the best-performing coating. Lastly, high-temperature coating characterization was performed up to 450 ˚C for one in-house deposited coating (nitrogen gas pressure of 4 Pa, bias voltage of -50 V) and one commercial coating. The results showed that a coating that has low H/E ratio (without compromising elastic modulus), high plasticity index, high toughness, moderate residual stress and low roughness effectively minimizes issues related to sticking and BUE formation and retains coating properties at high temperatures.

With the increasing complexity in construction projects, monitoring project schedule and managing projects effectively is becoming increasingly important. Most projects being deadline oriented, timely completion becomes a must. Like every industry, the construction industry too lays a lot of emphasis on timely completion which makes it necessary to monitor the project schedule very closely. A schedule overrun is never predicted at the start of the project but during the course of the project, even the slightest change can result in delays. As per the current scheduling practices, float is considered free. It is an expiring resource and hence the party to the use the float first owns the float. The concept endorsed by the court for analyzing delay claims is the proximate cause concept. As per this concept, the party which is the immediate cause to a particular delay is held responsible for that delay irrespective of what has happened before in the project. Due the ambiguous nature of its interpretation, the present concept on float management has now become one the primary reasons for disputes amongst the participating parties. Parties in contract are always trying to appropriate float to suit their interests. This is why total float management has gained this level of importance in today's industry. To handle this issue of total float management more efficiently, Dr. Prateapusanond (2003) proposes a new concept of total float management as an effort towards a more fair and equitable system. This concept respects the dynamic nature of construction projects and recognizes float to be an asset for both parties. The new concept proposes to allocate float in the ratio 50:50 between the parties at the start of the project. This pre-allocated float owned by each party is called the Allowable Total Float (ATF). The implementation of this concept ensures that the parties are now aware that consumption of float in a way that it affects critical activities will expose them potential damages. This concept is an effort towards a more fair and equitable system for total float management. It appears impressive on paper but its practicality and applicability remains a major concern. This research is aimed at testing the practicality of the proposed concept of pre-allocation of total float. It introduces bookkeeping procedures that will facilitate the application of the concept of Pre-allocation of total float. These procedures have been developed and tested on certain case studies to make sure that they are robust. Once their ability to handle scheduling issues is determined, the bookkeeping procedure along with the concept of pre-allocation of total float is applied to a real construction project. This research presents an in depth analysis of the nature of the proposed concept of pre-allocation of total float, the scheduling issues which this concept does not address to, and certain assumptions which could be used in conjunction with the present concept to make it robust in nature. / Master of Science

A criação de programas federais voltados para o desenvolvimento da infraestrutura brasileira no final da década passada resultou no aquecimento do setor de construção civil. Nesse contexto, o sistema de paredes de concreto moldadas no local se destacou devido à sua alta produtividade e repetitividade. Os requisitos e procedimentos para o dimensionamento de paredes de concreto moldadas no local são contemplados na NBR 16055:2012. Dentre as abordagens consideradas nessa norma, ressalta-se a recomendação do uso de concreto autoadensável. No entanto, alguns pontos de interesse não são contemplados na regulamentação vigente como, por exemplo, a incorporação de ar na composição do concreto, bem como os limites de teores de ar incorporado. Assim, a presente pesquisa busca avaliar a influência da incorporação de ar no comportamento de concretos autoadensáveis destinados à execução de paredes de concreto moldadas no local. Para isso, foram produzidos dois traços de concreto autoadensável de classes de resistência C25 e C40 e, a partir de cada um deles, produzidos outros dois traços modificados com aditivo incorporador de ar, variando o teor de ar incorporado, em um total de seis misturas cujas propriedades foram avaliadas tanto no estado fresco quanto no estado endurecido. Além disso, foram moldadas paredes de concreto a fim de analisar a estrutura interna do material com aparelho de ultrassom e o acabamento superficial do elemento por meio de análise de imagens. No caso da classe C25, os resultados demonstram que a influência do teor de ar para os traços modificados foi tão significativa que os concretos produzidos se tornaram inadequados para uso estrutural. Por outro lado, apesar da elevada perda de resistência à compressão aos 28 dias, os dois traços produzidos com incorporação de ar no concreto de classe C40 se adequam às recomendações da NBR 16055:2012. Alia-se a isso o fato de que, quando da execução das paredes em laboratório, os concretos utilizados demonstraram grande capacidade de preenchimento, resultando em elementos com bom acabamento superficial e estrutura interna homogênea, mesmo em regiões de difícil acesso. Sendo assim, o presente trabalho propõe traços muito promissores para utilização em paredes de concreto moldadas no local. / The creation of federal programs aimed at the development of Brazilian infrastructure at the end of the last decade resulted in the heating of civil construction sector. In this context, the system of concrete walls cast in place stood out due to its high productivity and repetitiveness. The requirements and procedures for the design of concrete walls cast in place are contemplated in the NBR 16055:2012. Among the several approaches considered in this code, the recommendation for the use of self-compacting concrete is emphasized. However, some points of interest are not considered in the current regulations, such as the incorporation of air in the concrete composition, as well as the limits for entrained air contents. Thus, the present research seeks to evaluate the influence of air entrainment in the behaviour of self-compacting concrete for the construction of concrete walls cast in place. For this, two self-compacting concrete mixes design of strength classes C25 and C40 were produced and, from each of them, two other mixes modified with air entraining admixture were produced, varying the entrained air content, in a total of six mixtures whose properties were evaluated in both fresh and hardened state. In addition, concrete walls were cast to analyse the internal structure with ultrasonic equipment and the element surface finish by image analysis. In the case of class C25, the results demonstrate that the influence of the air content for the modified mixes was so great that the concretes produced became inappropriate for structural use. On the other hand, despite the high loss of compressive strength at 28 days, the two mixes produced with entrained air in the concrete of class C40 respect the recommendations of the NBR 16055:2012. In addition, when the walls were cast in laboratory, the concretes used showed great filling capacity, resulting in structures with good surface finish and homogeneous internal structure, even in difficult access regions. Therefore, the present work proposes very promising mixes for use in concrete walls cast in place.

Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2017-03-23T12:34:35Z No. of bitstreams: 1 RENAN SERRALVO CAMPOS.pdf: 14804663 bytes, checksum: d21aa4db3ac6aef546c6f30dc795691b (MD5) / Made available in DSpace on 2017-03-23T12:34:35Z (GMT). No. of bitstreams: 1 RENAN SERRALVO CAMPOS.pdf: 14804663 bytes, checksum: d21aa4db3ac6aef546c6f30dc795691b (MD5) Previous issue date: 2017-02-15 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The high consumption of natural resources and energy, coupled with the significant amount of solid waste generated by the construction activities, makes this sector one of the most responsible for environmental impacts. The recycling of mineral fraction of construction and demolition wastes (CDW), in form of aggregates, is seen as an alternative to reduce these impacts. In this way, the aim of this study was to investigate the influence of recycled aggregates on the rheological, mechanical properties, physical indexes and surface finish of self-compacting concrete (SCC). For this, eight compositions of SCC were analyzed, using the Repette-Melo method and Alfred model, which is based on the concept of particle packing, for the mix design of concretes. Thus, two reference mixtures, composed only of natural aggregates, were established. The other mixtures used recycled fine and/or coarse aggregates instead of natural aggregates, at 20% by mass. The properties of fresh concrete were evaluated with respect to the flowability, viscosity (measure of the speed of flow), passing ability and segregation resistance. In hardened state, compressive strength, splitting tensile strength, static modulus of elasticity, water absorption by immersion and by capillarity, density and voids index were determined. In this study, rheological characterization of cement pastes and mortars destined to the production of SCC was also carried out using rotational rheometry. Rheological characterization of pastes, mortars and concretes is a suitable way to evaluate the behavior of these composites in fresh state, providing useful information that will aid in mix design process and quality control. Another property evaluated was the surface finish of concretes and mortars and the possible correlation of this with the rheological parameters. Through the results obtained it was possible to verify the loss of fluidity in mortars and concretes that used recycled aggregates. Regarding the mechanical properties, different behaviors were observed in concretes produced with recycled aggregates: those that were dosed by Repette-Melo method did not show a significant decrease of these properties; while the concretes dosed by the concept of particle packing exhibited a great reduction in mechanical properties. Concretes produced with recycled aggregates still showed an increase in water absorption by immersion, voids index and capillary absorption, when comparing to the respective reference mixtures. It was possible to observe a good linear correlation between surface finish and shear stress of mortars. In the case of concretes, the slump-flow was the property that best correlated with the quality of surface finish. / O elevado consumo de recursos naturais e energia, associado ao expressivo montante de res?duos s?lidos gerados pelas atividades de constru??o civil faz deste setor um dos maiores respons?veis por impactos ambientais. A reciclagem da fra??o mineral dos res?duos de constru??o e demoli??o (RCD), na forma de agregados, ? vista como uma alternativa para a diminui??o destes impactos. Isto posto, o objetivo deste estudo foi investigar a influ?ncia dos agregados reciclados nas propriedades reol?gicas, mec?nicas, ?ndices f?sicos e no acabamento superficial de concretos autoadens?veis (CAA). Para isso, foram analisadas oito composi??es de CAA, sendo empregados o m?todo de Repette-Melo e o modelo de Alfred, que tem por base o conceito de empacotamento de part?culas, para a dosagem dos concretos. Assim, foram estabelecidos dois tra?os de refer?ncia, compostos apenas por agregados naturais. As demais misturas utilizaram agregados mi?dos e/ou gra?dos reciclados em substitui??o aos agregados naturais, no teor de 20%, em massa. As propriedades do concreto fresco foram avaliadas no que diz respeito ao espalhamento, tempo de escoamento, habilidade passante e resist?ncia ? segrega??o. No estado endurecido foram determinadas as resist?ncias ? compress?o e ? tra??o por compress?o diametral, o m?dulo de elasticidade est?tico, a absor??o de ?gua por imers?o e por capilaridade, a massa espec?fica e o ?ndice de vazios. Neste estudo tamb?m foi realizada a caracteriza??o reol?gica das pastas de cimento e das argamassas destinadas ? produ??o dos CAA?s, por meio de reometria rotacional. A caracteriza??o reol?gica de pastas, argamassas e concretos ? uma forma adequada para avaliar o comportamento destes comp?sitos no estado fresco, podendo prover informa??es ?teis que auxiliar?o no processo de dosagem e controle de qualidade. Outra propriedade avaliada foi o acabamento superficial dos concretos e argamassas e a poss?vel correla??o deste com os par?metros reol?gicos. Atrav?s dos resultados obtidos foi poss?vel constatar perda de fluidez nas argamassas e concretos que empregaram agregados reciclados. No que tange as propriedades mec?nicas, foram observados comportamentos distintos nos concretos produzidos com agregados reciclados: ?queles dosados pelo m?todo de Repette-Melo n?o apresentaram decr?scimo significativo destas propriedades; enquanto que, os concretos dosados com base no conceito de empacotamento de part?culas exibiram grande redu??o nas propriedades mec?nicas avaliadas. Os concretos produzidos com agregados reciclados ainda apresentaram aumento na absor??o de ?gua por imers?o, no ?ndice de vazios e na absor??o capilar, quando comparados aos respectivos tra?os de refer?ncia. Foi poss?vel observar boa correla??o linear entre o acabamento superficial e a tens?o de cisalhamento das argamassas. No caso dos concretos, o di?metro de espalhamento foi a propriedade que melhor se correlacionou com a qualidade do acabamento superficial.

With increasing environmental awareness, the desire to protect human beings and the environment from adverse effects induced by dispersed metals has become an issue of great concern and interest. New policies, such as REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) within the European Community, have been implemented to reduce hazards posed by the use of chemicals on producers and downstream users. The generation of exposure assessment data and relevant test procedures able to simulate realistic scenarios are essential in such legislative actions. This doctoral study was initiated to fill knowledge gaps related to the metal release process of stainless steels. A wide range of stainless steel grades, fourteen in total, were investigated. They cover a very broad range of applications, and the focus in the thesis was to simulate a few selected exposure scenarios: precipitation, the human body and food intake. Comparisons were made between metal release from stainless steel alloys and the pure metals that constitute each stainless steel in order to explore the differences between alloys and pure metals, and to provide quantitative data on metal release rates of different alloy constituents. Because of similar surface properties between stainless steel and pure chromium, this metal exhibits similar release rates, whereas iron and nickel exhibit significantly lower release rates as alloy components than as pure metals. Detailed studies were also performed to elucidate possible relations between metal release and steel surface properties. Key parameters turned out to be chromium enrichment of the self-passivating surface film, surface roughness, the electrochemically active surface area and the microstructure of the steel substrate. The degree of metal release increased with decreasing chromium content in the surface oxide, increasing surface roughness, and increasing presence of inhomogeneities in the bulk matrix. More detailed studies were initiated to possibly correlate the nucleation of metastable pits and the extent of metal release. Evidence was given that metastable pits exist even when the stainless steel is passive, and may cause extremely short-lived bursts of released metal before the surface film repassivates again. / QC 20100810

To facilitate the transition of Stereolithography (SLA) into the manufacturing domain and to increase its appeal to the micro manufacturing industry, process repeatability and surface finish need to be improved. Researchers have mostly focused on improving SLA surface finish within the capabilities of commercially available SLA machines. The capabilities of these machines are limited and a machine-specific approach for improving surface finish is based purely on empirical data. In order to improve surface finish of the SLA process, a more systematic approach that will incorporate process parameters is needed. To achieve this, the contribution of different laser and process parameters, such as laser beam angle, irradiance distribution, and scan speed, to SLA resolution and indirectly to surface finish, need to be quantified and incorporated into an analytical model. In response, a dynamic analytical SLA cure model has been developed. This model has been applied to SLA geometries of interest. Using flat surfaces, the efficacy of the model has been computationally and experimentally demonstrated. The model has been applied to process planning as a computational inverse design method by using parameter estimation techniques, where surface finish improvement on slanted surfaces has been achieved. The efficacy of this model and its improvement over the traditional cure models has been demonstrated computationally and experimentally. Based on the experimental results, use of the analytical model in process planning achieves an order of magnitude improvement in surface roughness average of SLA parts. The intellectual contributions of this research are the development of an analytical SLA cure model and the application of this model to process planning along with inverse design techniques for parameter estimation and subsequent surface finish improvement.

L’eau supercritique peut être utilisée comme caloporteur à haute pression pour améliorer le rendement des centrales électriques. Pour un concept de réacteur nucléaire, la durée de vie des matériaux est un paramètre important en termes de sécurité. Par conséquent, les critères de sélection des matériaux pour un concept de réacteur à l’eau supercritique concernent les propriétés mécaniques à haute température pour une bonne tenue au fluage et à l’irradiation mais également une résistance à la corrosion généralisée et à la corrosion sous contrainte. Ce travail à pour objectif d’améliorer la compréhension des mécanismes de corrosion en eau supercritique à 600°C et 25 MPa pour des alliages c.f.c contenant du fer, du nickel et du chrome. Des essais de corrosion ont été réalisés sur des autoclaves échantillons d’alliages 316L et 690 en prenant en compte l’état de surface. Les couches d’oxydes formées ont été décrites en termes de morphologie, de composition et de structure, après caractérisations par microscopie électronique à balayage, par spectroscopie à décharge luminescente et par diffraction des rayons X. Si un comportement de type gazeux de l’eau supercritique est attendu dans les conditions d’essai, les résultats montrent une dissolution significative de certains éléments de l’alliage. Par conséquent, la corrosion en eau supercritique peut être considérée comme similaire à la corrosion aqueuse avec un effet de la température qui peut influencer la diffusion en phase solide par exemple. Pour l’alliage 690, la couche d’oxyde protectrice formée sur une surface polie est composée de chromine et surmontée d’un chromite ou d’un spinelle mixte de nickel et de fer. La double couche d’oxyde formée sur une surface de même finition pour l’alliage 316L semble moins protectrice. La couche externe de magnétite est poreuse et la couche interne riche en chrome est non homogène. Pour chaque alliage, l’étude des mécanismes de diffusion, grâce à des expériences utilisant des marqueurs ou des traceurs, révèle une croissance de la couche d’oxyde contrôlée par un processus anionique. Cependant, l’état de surface influence fortement les mécanismes de formation des couches d’oxyde. La comparaison des résultats sur l’acier suggère qu’il y a une concurrence entre l’oxydation du fer et celle du chrome. Une quantité suffisante de chrome est nécessaire pour former une fine couche d’oxyde protectrice. Les surfaces très déformées ou à microstructure à grains très fins conduisent à des fines couches d’oxyde de chrome, grâce à une forte densité de site de germination ou grâce aux courts-circuits de diffusion du chrome. L’état de surface est donc déterminant pour l’acier mais le même paramètre engendre des effets différents pour l’alliage à base de nickel. Les surfaces usinées deviennent sensibles à une oxydation interne du chrome, même si une fine couche d’oxyde continue et riche en chrome et manganèse se forme. Ce phénomène suggère une diffusion accélérée concurrentielle entre l’oxygène et le chrome. Pour conclure, ce travail propose un mécanisme de croissance de la couche d’oxyde dans chaque cas et discute des conditions favorables à la formation d’une couche d’oxyde protectrice riche en chrome dans l’optique d’une application au réacteur à eau supercritique. / Supercritical water can be use as a high pressure coolant in order to improve the thermodynamic efficiency of power plants. For nuclear concept, lifetime is an important safety parameter for materials. Thus materials selection criteria concern high temperature yield stress, creep resistance, resistance to irradiation embrittlement and also to both uniform corrosion and stress corrosion cracking.This study aims for supplying a new insight on uniform corrosion mechanism of Fe-Ni-Cr f.c.c. alloys in deaerated supercritical water at 600°C and 25MPa. Corrosion tests were performed on 316L and 690 alloys as sample autoclaves taking into account the effect of surface finishes. Morphologies, compositions and crystallographic structure of the oxides were determined using FEG scanning electron microscopy, glow discharge spectroscopy and X-ray diffraction. If supercritical water is expected to have a gas-like behaviour in the test conditions, the results show a significant dissolution of the alloy species. Thus the corrosion in supercritical water can be considered similar to corrosion in under-critical water assuming the higher temperature and its effect on the solid state diffusion. For alloy 690, the protective oxide layer formed on polished surface consists of a chromia film topped with an iron and nickel mixed chromite or spinel. The double oxide layer formed on 316L steel seems less protective with an outer porous layer of magnetite and an inhomogeneous Cr-rich inner layer. For each alloy, the study of the inner protective scale growth mechanisms by marker or tracer experiments reveals that diffusion in the oxide scale is governed by an anionic process. However, surface finishes impact deeply the growth mechanisms. Comparisons between the results for the steel suggest that there is a competition between the oxidation of iron and chromium in supercritical water. Sufficient available chromium is required in order to form a thin oxide layer. Highly deformed or ultra fine microstructure surfaces lead to thin chromium rich oxide layers thanks to either diffusion short circuiting or increasing Cr oxide nucleation site. The nature of the surface is a determining factor in the steel instance. The same parameter breeds different effects for the Ni-based alloy. Machined surfaces lead to internal oxidation on alloy 690 even if a thin Cr and Mn rich oxide scale is formed. Competitive diffusion of oxygen and Cr species through the diffusion short circuit paths of the alloy is suggested. This work proposes oxide growth mechanisms for each case. Finally the conditions leading to the formation of chromium-rich protective oxide films in supercritical water are discussed.

Purpose: BIM have been criticised as a standalone framework and the believe is that the next step in BIM development is cloud computing. The technology simplify planning of a sustainable construction and hasten the building process through a collaborative friendly information management among different project actors. The implementation of the technology hasn’t been that noticeable since companies are struggling to understanding the technologies contribution. The goal of this research is therefore to investigate the potential of using cloud technology in architects daily work with room finish schedule. Method: To answer the goal of the study, interviews about room finish schedules have been made with five architect companies to collect empirical data. The company's internal documents of room finish schedule have been analysed and the research also makes a literature study and an observation of the cloud service BIMeye. Findings: The study shows that the main differences between an analogue and digital approach are: the link to the model, input of information and management of revisions. The companies have generally a positive attitude towards the technology, but there are doubts about changing their way of working. The cloud service BIMeye meets the companies needs and has great potential to make several tasks, that are considered time consuming in today´s work, more efficient, such as lay-up of rooms, input of information, review of conflicting documents and management of revisions. This mainly through the database's connection to the model and the database's way of managing information more automated. Implications: The conclusion that can be made is that great potential is seen with cloud services as a working method for producing room finish schedules. The transition process to cloud services implies a change of working method but not in the final result. Where cloud services entail additional work in the model to enable a connection to the description, but at the same time contributes to an automatic input of information about rooms. Another change in working method is the ability of cloud services to create parameters that differs from the otherwise analogue paper-work. Revisions in the database get a break through throughout the whole description, in contrast to individual adjustments in the document. Recommendations as a result of the study is to inform companies about the possibilities and impact the technology has on their work. In order to achieve an overall perspective in the industry, new solutions are required so that companies see internal profits with the implementation. Limitations: The result is considered to be applicable to other architect firms since it has appeared from interviews and document analyses that the companies work in similar ways. However, whether the result of the test of BIMeye can be applied to other cloud services is uncertain. The research’s limitation to disregard investment cost has restrict the study as it is a significant factor when implementing new technology. / Syfte: BIM har kritiserats för sitt ensamstående ramverk och nästa steg i BIM utvecklingen anses vara molnteknologin. Tekniken förenklar planering av ett hållbart byggande och påskyndar byggprocessen genom en mer sammarbetsvänlig informationshantering mellan olika projektdeltagare. Implementeringen av tekniken har inte varit så märkbar, detta då företagen har svårt att förstå dess bidrag. Målet med arbetet är därför att undersöka möjligheterna att använda molnteknologin i arkitekters arbete med rumsbeskrivningar. Metod:  För att besvara målet har intervjuer om rumsbeskrivningar gjorts på fem arkitektföretag för att samla in empiri. Företagens interna rumsbeskrivningsdokument har analyserats och i undersökningen görs även en litteraturstudie och en observation av molntjänsten BIMeye. Resultat: Studien visar att de största skillnaderna mellan ett analogt och digitalt tillvägagångsätt är kopplingen till modell, inmatning av information och hantering av revideringar. Företagen har överlag en positiv inställning till tekniken men det finns tveksamheter till att ändra sitt arbetssätt. Molntjänsten BIMeye uppfyller de önskemål som företagen har och har stor potential till att effektivisera flertalet arbetsmoment som anses tidskrävande i dagens arbete, såsom uppläggning av rum, inmatning av information, granskning av motstridiga handlingar och hantering av revideringar. Detta främst genom databasens koppling till modell och databasens sätt att hantera information mer automatiserat. Konsekvenser: Slutsatsen är att det finns en stor potential med molntjänster som arbetsmetod vid framtagning av rumsbeskrivningar. Övergångsprocessen till molntjänster innebär förändring av arbetsmetod, men inte i slutresultat. Där molntjänster medför ett merarbete i modellen för att möjliggöra en koppling till beskrivningen, men medför samtidigt automatisk inmatning av information om rum. En annan förändring i arbetsmetod är molntjänsters möjlighet att skapa parametrar som skiljer sig från det annars analoga skrivarbetet. Revideringar i databasen får genomslag i hela beskrivningen, tillskillnad från enskilda justeringar i dokumentet. Rekommendationer till följd av arbetet blir att upplysa företagen om teknikens möjligheter och påverkan på arbetet. För att uppnå ett helhetsperspektiv i branschen behövs nya lösningar så att företagen ser interna vinningar med implementeringen. Begränsningar: Resultatet anses applicerbart på fler arkitektföretag än Krook &amp; Tjäder då det framgått från intervjuer och dokumentanalyser att företagen arbetar på liknande sätt. Däremot huruvida resultatet från testet av BIMeye går att applicera på andra molntjänster är oviss. Arbetets avgränsning till att bortse från investeringskostnader har begränsat arbetet då det är en betydande faktor vid implementering av ny teknik.