The reliability of modern gas turbine engines is largely due to careful damage tolerant design a method of structural design based on the assumption that flaws (cracks) exist in any structure and will continue to grow with usage. With proper monitoring, largely in the form of periodic inspections at conservative intervals reliability and safety is maintained. These methods while reliable can lead to the early retirement of some components and unforeseen failure if design assumptions fail to reflect reality. With improvements to sensor and computing technology there is a growing interest in a system that could continuously monitor the health of structural aircraft as well as forecast future damage accumulation in real-time. Through the use of two-dimensional and three-dimensional numerical modeling the initial goals and findings for this continued work include: (a) establishing measurable parameters directly linked to the health of the blade and (b) the feasibility of detecting accumulated damage to the structural material and thermal barrier coating as well as the onset of damage causing structural failure.

The purpose of this research work was to develop a nozzle capable of depositing dense CoNiCrAlY coatings via cold gas dynamic spray (CGDS) as well as compare the oxidation performance of bond coats manufactured by CGDS, high-velocity oxy-fuel (HVOF) and air plasma spray (APS) at temperatures of 1000°C and 1100°C. The work was divided in two sections, the design and manufacturing of a CGDS nozzle with an optimal profile for the deposition of CoNiCrAlY powders and the comparison of the oxidation performance of CoNiCrAlY bond coats. Throughout this work, it was shown that the quality of coatings deposited via CGDS can be increased by the use of a nozzle of optimal profile and that early formation of protective α-Al2O3 due to an oxidation temperature of 1100°C as opposed to 1000°C is beneficial to the overall oxidation performance of CoNiCrAlY coatings.

Made available in DSpace on 2015-03-26T13:55:13Z (GMT). No. of bitstreams: 1 texto completo.pdf: 545117 bytes, checksum: 7ad3378bf0c824361e4be8d29161719b (MD5) Previous issue date: 2012-07-12 / The purpose this work was to evaluate milk quality in different production systems and its variation throughout the year. The database used in this work were from 943 milk farms from different regions: south, midwest and central of state of Minas Gerais and Vale Paraíba, state of São Paulo. Data totaled 18.026 samples, collected between January (2009) and September (2011), and it was granted by Danone Firm. The milk farms were classified in three different production systems: confined, semi-confined and extensive system (grass fed). Somatic cells count (SCC), total bacterial count (TBC) and milk protein and fat contents were evaluated. The data was analyzed in a completely randomized design in a repeated measured scheme, and theproc MIXED procedure of SAS (2008) was used. The production system did not affect milk protein and fat contents, neither the SCC. However, the production system affected the TBC, indicating that TBC is related to the available structure for feeding animals. It is possible that the results are consequence of a payment program for quality, whichwas started by the milk industry in 2002. Seasonal variations in results of SCC, CBT and milk protein and fat contents were observed. The milk protein content was greater between March and June, while the milk fat content was greater between May and August. TBC and SCC were greater between December and March. In conclusion, production system does not affect milk protein and fat contents, neither SCC. However, confined systems have better TBC results. Furthermore, month and year affect the milk quality (TBC, SCC, milk protein and fat content results), where better results are observed in cold seasons. / Objetivou-se avaliar a qualidade do leite cru em diferentes sistemas de produção e sua variação ao longo do ano. Os dados utilizados nesse trabalho foram obtidos de 943 propriedades leiteiras das regiões do Sul de Minas, Centro-Oeste e Central Mineira no estado de Minas Gerais e na região do Vale do Paraíba no estado de São Paulo. Os mesmos foram concedidos pela Empresa Danone, em um total de 18.026 amostras, no período de janeiro de 2009 a setembro de 2011. As propriedades foram divididas em sistema de produção confinado, semi-confinado e extensivo. Os itens avaliados foram contagem de células somáticas (CCS), contagem bacteriana total (CBT) e teores de proteína e gordura. Os dados foram analisados em esquema de medidas repetidas no tempo, utilizando o procedimento proc MIXED do SAS (2008). Não houve efeito de sistema de produção sobre os teores de proteína, gordura e CCS. Já a CBT foi afetada pelo sistema de produção estando relacionada com o tipo de estrutura para alimentar os animais. Possivelmente, os resultados são consequência do programa de pagamento por qualidade implantando pelo laticínio desde o ano de 2002. Foram encontradas variações sazonais de CCS, CBT, proteína e gordura; sendo os valores de proteína mais elevados de Março a Junho, os valores de gordura mais elevados de Maio a Agosto, os valores de CBT e CCS mais elevados de Dezembro a Março.Conclui-se que o sistema de produção não interfere na porcentagem de gordura e proteína e CCS do leite. No entanto, sistemas confinados apresentam melhor padrão de CBT. Conclui-se, também, que tanto mês quanto ano são fatores que interferem na CBT, CCS, proteína e gordura do leite, sendo os melhores padrões encontrados nas épocas mais frias do ano.

Le système barrière thermique, permettant la protection des aubes mobiles des turbines aéronautiques, est un système dont l'élaboration est complexe et nécessite de nombreuses étapes. L'utilisation du spark plasma sintering (SPS) a permis de réaliser des systèmes barrière thermique complets en une étape unique. Au-delà des possibilités industrielles de cette méthode, le SPS s'est avéré un outil de recherche précieux pour rapidement tester un vaste champ de compositions et d'ajouts d'éléments réactifs. Les premier essais et la modélisation de la diffusion dans le SPS ont permis de prévoir les phases du revêtement suite à l'étape de SPS. Les travaux se sont ensuite focalisés sur l'optimisation d'une composition de sous couche γ-γ' riche en platine dopée avec des éléments réactifs sur un substrat d'AM1. L'analyse chimique des revêtements SPS a révélé des taux de pollutions en soufre et carbone extrêmement faibles. Au vu de l'influence néfaste de ces éléments sur la tenue en oxydation cyclique ces analyses mettent en valeur la qualité des revêtements élaborés. Les performances des sous couches dopées, avec notamment du hafnium, de l'yttrium et du zirconium ont été évaluées lors d'essais de cyclage thermique à 1100°C sous air. La composition de revêtement γ-γ' la plus prometteuse a ensuite été comparée au système industriel β-(NiPt)Al avec la même barrière thermique de zircone yttriée déposée par EBPVD et le même substrat d'AM1. Les résultats obtenus montre une meilleure durée de vie des systèmes TBC avec sous couches γ-γ'. Par contre la remontée importante des éléments du superalliage dans le revêtement influence la durée de vie du système TBC comme cela a été montré par des dépôts conduits sur d'autres nuances de superalliages à base de nickel. Ces résultats montrent que pour les revêtements γ-γ' la prise en compte du revêtement dans le développement d'un superalliage est essentielle. / To protect turbines blades from excessive oxidation and to lower the temperature at the blade surface, a multilayer coating system has been developed in the past, i.e. the thermal barrier coating. The fabrication of TBC is expensive and demands numerous process steps. In this study, bond coatings have been fabricated by spark plasma sintering in a single step. This fast fabrication process permits to test a large range of bond coating compositions with different reactive elements such as Zr, Y and Hf on AM1 nickel base superalloy. From the first results, the data related to the diffusion during the SPS were calculated to predict the coating phases. Impurities levels were measured after SPS fabrication. Sulphur and carbon concentration were very low. These results highlight the great quality of coating made by spark plasma sintering, more particularly with a top coat also made by SPS. Then, a composition of γ-γ’ coating has been optimized for high life span during thermal cycling. The thermal cycling at 1100°C of TBC system with this optimized γ-γ’ bond coatings give better life span than the conventional system with β-(Ni,Pt)Al phase bond coating. After long thermal cycling, >1000*1h cycles, chemical elements from the substrate can diffuse in the thermally grown oxide, leading to its delamination. Thus, for increasing the life span of the whole system the bond coating has to be considered during the superalloy development.

Tuberkulos (tbc) är en luftburen droppsmitta orsakad av mykobakterium tuberkulosis. Tbc är den sjukdom som efter AIDS orsakar flest dödsfall, trots att botande behandling finns. Behandlingen är krävande för den tbc-smittade att genomgå och bygger på en kombination av en rad antibiotika som måste intas under minst sex månader. Ett avvikande i behandlingen kan resultera i att mykobakterium tuberkulosis blir resistent mot de ordinerade antibiotika. Följsamhet av långtidsbehandlingar som tbc-behandling graderas till 50 %. Syftet med litteraturstudien var att ur ett globalt perspektiv beskriva hur sjuksköterskan kan påverka följsamhet vid tbc-behandling i syfte att minska resistensutvecklingen av mykobakterium tuberkulosis. Studien genomfördes som en litteraturstudie där 12 vetenskapliga artiklar granskades och analyserades. Resultatet visar tydligt att specifika faktorer påverkar följsamhet och därigenom resistensutvecklingen. Faktorerna innefattar patientundervisning, behandlingsstrategier, omgivningens påverkan och stöd.  Undervisningen resulterar i att patienten får ökad förståelse för behandlingen. För att minska stigmatiseringen och det lidande den innebär för den tbc-smittade är även omgivningen i behov av ökad kunskap och information om tbc. Ett flertal studier visar att DOTS-strategin är betydelsefull för ökad följsamhet vid antituberkulos behandling. Litteraturstudien medför ett förslag om att sjuksköterskeprogrammet ska öka fokuseringen på följsamhet vid läkemedelsanvändning. Sjuksköterskan är i behov av att redan under grundutbildningen få kunskap om ansvarsfull antibiotikahantering som leder till en följsamhetsomtanke. / Tuberculosis (TB) is an airborne droplet infection caused by mycobacterium tuberculosis. TB is the disease after AIDS that is most deadly, even though curative treatment exists. The treatment is demanding for the TB-infected to undergo and consists of a combination of a number of antibiotics that must be administered for at least six months. A dissenting in anti-tuberculosis treatment might result in mycobacterium tuberculosis strains that are resistant to antibiotics. As adherence to long-term treatment is graded at a low percentage (50 %) the aim of the literature study was from a global perspective to develop a working-strategy for nurses that promote compliance in TB-treatment in order to reduce resistance development of mycobacterium tuberculosis. The study was conducted as a literature study where 12 research articles were reviewed and analyzed. The results describe specific factors that are essential to compliance. These factors comprise patient education, treatment strategies, social influences and support. As knowledge gives the patient a better understanding for the treatment it provokes compliance. The social environment of the TB-infected patient demands increased knowledge in order to reduce stigma. Several studies show that the DOTS strategy is important for increasing compliance in anti-tuberculosis treatment. The literature study results in a proposal for the nursing program to focus more on compliance in taking medication. The nursing program’s attendants need to gain knowledge about prudent antibiotic treatment that leads to a compliance concern.

The reliability of modern gas turbine engines is largely due to careful damage tolerant design a method of structural design based on the assumption that flaws (cracks) exist in any structure and will continue to grow with usage. With proper monitoring, largely in the form of periodic inspections at conservative intervals reliability and safety is maintained. These methods while reliable can lead to the early retirement of some components and unforeseen failure if design assumptions fail to reflect reality. With improvements to sensor and computing technology there is a growing interest in a system that could continuously monitor the health of structural aircraft as well as forecast future damage accumulation in real-time. Through the use of two-dimensional and three-dimensional numerical modeling the initial goals and findings for this continued work include: (a) establishing measurable parameters directly linked to the health of the blade and (b) the feasibility of detecting accumulated damage to the structural material and thermal barrier coating as well as the onset of damage causing structural failure.

The purpose of this research work was to develop a nozzle capable of depositing dense CoNiCrAlY coatings via cold gas dynamic spray (CGDS) as well as compare the oxidation performance of bond coats manufactured by CGDS, high-velocity oxy-fuel (HVOF) and air plasma spray (APS) at temperatures of 1000°C and 1100°C. The work was divided in two sections, the design and manufacturing of a CGDS nozzle with an optimal profile for the deposition of CoNiCrAlY powders and the comparison of the oxidation performance of CoNiCrAlY bond coats. Throughout this work, it was shown that the quality of coatings deposited via CGDS can be increased by the use of a nozzle of optimal profile and that early formation of protective α-Al2O3 due to an oxidation temperature of 1100°C as opposed to 1000°C is beneficial to the overall oxidation performance of CoNiCrAlY coatings.

<p dir="ltr">Thermal Barrier Coatings (TBC) represent the key technology enabling greater efficiency and performance in jet engines and gas turbines. In modern engines, TBCs allow gas temperatures to exceed 1700°C, well above the point at which the structural alloys lose their strength. By insulating the underlying nickel-alloy components from the extreme heat generated during combustion, TBCs support a larger temperature gradient. </p><p dir="ltr">As operating temperatures are further increased to improve performance, thermal radiation becomes a more substantial carrier of heat. However, conventional TBCs are designed to provide a single barrier against only the phonon-mediated conductive heat flux, leaving the photonic radiative heat transfer largely unmitigated. We propose a Thermal Dual Barrier Coating (TDBC) to simultaneously suppress the phononic and photonic heat transfer by integrating a reflective thermal metamaterial into an independent phonon-optimized TBC.</p><p dir="ltr">The main obstacle to achieving the TDBC is in the selection of adequate reflective materials in the metamaterial. Conventional refractory metals that demonstrate the greatest stability and functionality in thermal metamaterials show instability under harsher environments. In our work, we identified and studied the key ideas, metrics, and challenges in metamaterials based on alternating layers of refractory metals and oxides for TDBC applications.</p><p dir="ltr">Our work emphasizes oxidation as a crucial degradation factor that is unavoidable in our assessment of the metamaterials. In formulating this problem, we bring the concept of oxidation-resistance through passivation to the forefront of material selection. We emphasize the passivative and oxidative properties of the metallic layer as a critical determinant in overall stability. In our work, we assess the enhancements in stability brought via passivation through the Pilling-Bedworth Ratio. We then propose the use of metal silicides in metamaterials as an overlooked class of oxidation-resistant IR reflective materials that operate through a more complex passivation method. We demonstrate strong stability in the structural integrity as well as the infrared responses of the metamaterials at up to 1200°C in atmospheric and oxidative environments.</p><p dir="ltr">After establishing the viability of metal silicides in wide-area thin films, we explore their viability in more complex thermal structures. We fabricate metal silicide metasurfaces for directional thermal emission. We demonstrate a grating structure that exhibits enhanced structural stability and maintains directional modes in the mid-IR after annealing at 1000°C.</p>

Pt-aluminide (PtAl) coatings form an integral part of thermal barrier coating (TBC) systems that are applied on Ni-based superalloy components operating in the hot sections of gas turbine engines. These coatings serve as a bond coat between the superalloy substrate and the ceramic yttrium stabilized zirconia (YSZ) coating in the TBC system and provide oxidation resistance to the superalloy component during service at high temperatures. The PtAl coatings are formed by the diffusion aluminizing process and form an integral part of the superalloy substrate. The microstructure of the PtAl coatings is heavily graded in composition as well as phase constitution. The matrix phase of the coating is constituted of the B2-NiAl phase. Pt, in the coating, is present as a separate PtAl2 phase as well as in solid solution in B2-NiAl. The oxidation resistance of the PtAl bond coat is derived from the B2-NiAl phase. At high temperatures, Al from the B2-NiAl phase forms a regenerative layer of alumina on the coating surface which, thereby, lowers the overall oxidation rate of the superalloy substrate. The presence of Pt is beneficial in improving the adherence of the alumina scale to the surface and thereby enhancing the oxidation resistance of the coating. However, despite its excellent oxidation resistance, the B2-NiAl being an intermetallic phase, renders the PtAl coating brittle and imparts it with a high brittle-to-ductile-transition-temperature (BDTT). The PtAl coating, therefore, remains prone to cracking during service. The penetration of these cracks into the substrate is known to degrade the strain tolerance of the components. Evaluation of the mechanical behavior of these coatings, therefore, becomes important from the point of views of scientific understanding as well as application of these coatings in gas turbine engine components. Studies on the mechanical behavior of coatings have been mostly carried on coated bulk superalloy specimens. However, since the coating is brittle and the superalloy substrate more ductile when compared to the coating, the results obtained from these studies may not be representative of the coating. Therefore, it is imperative that the mechanical behavior of the coating in stand-alone condition, i.e. the free-standing coating specimen without any substrate attached to it, be evaluated for ascertaining the true mechanical response of the coating. Study of stand-alone bond coats involves complex specimen preparation techniques and challenging testing procedures. Therefore, reports on the evaluation of mechanical properties of stand-alone coatings are limited in open literature. Further, no systematic effort has so far been made to examine important aspects such as the effect of temperature and strain rate on the tensile behavior of these coatings. The deformation mechanisms associated with these bond coats have also not been reported in the literature. In light of the above, the present research study aims at evaluating the tensile behavior of free-standing PtAl coatings by the micro-tensile testing technique. The micro-tensile testing method was chosen for property evaluation because of its inherent ability to generate uniform strain in the specimen while testing, which makes the results easy to interpret. Further, since the technique offers the feasibility to test the entire graded PtAl coating in-situ, the results remain representative of the coating. Using the above testing technique, the tensile behavior of the PtAl coating has been evaluated at various temperatures and strain rates. The effect of strain rate on the BDTT of the coating has been ascertained. Further, the effect of Pt content on the tensile behavior of these coatings has also been evaluated. Attempts have been made to identify the mechanisms associated with tensile deformation and fracture in these coatings. The thesis is divided into nine chapters. Chapter 1 presents a brief introduction on the operating environment in gas turbine engines and the materials that are used in the hot sections of gas turbine engines. The degradation mechanisms taking place in the superalloy in gas turbine environments and the need for application of coatings has also been highlighted. The basic architecture of a typical thermal barrier coating (TBC) system applied on gas turbine engine components has been presented. The constituents of the TBC system, i.e. the ceramic YSZ coating, MCrAlY overlay as well as diffusion aluminide bond coats and, the various techniques adopted for the deposition of these coatings have been described in brief. Chapter 2 presents an overview of the literature relevant to this study. This chapter is divided into four sub-chapters. The formation of diffusion aluminide coatings on Ni-based superalloys has been described in the first sub-chapter. Emphasis has been laid on pack cementation process for the formation of the coatings. The fundamentals of pack aluminizing process, including the thermodynamic and kinetic aspects, have been mentioned in brief. The microstructural aspects of high activity and low activity plain aluminide and Pt-aluminide coatings have also been illustrated. The techniques applied for the mechanical testing of bond coats have been discussed in the second sub-chapter. The macro-scale testing techniques have been mentioned in brief. The small scale testing methods such as indentation, bend tests and micro-tensile testing have also been discussed in the context of evaluation of mechanical properties of bond coats. Since the matrix in the aluminide bond coats is constituted of the B2-NiAl phase, a description of the crystal structure and deformation characteristics of this phase including the flow behavior, ductility and fracture behavior has been mentioned in the third sub-chapter. In the fourth sub-chapter, reported literature on the tensile behavior and brittle-to-ductile-transition-temperature (BDTT) of diffusion aluminide bond coats has been discussed. In Chapter 3, details on experiments carried out for the formation of various coatings used in the present study and, their microstructural characterization, are provided. The method for extraction of stand-alone coating specimens and their testing is discussed. The microstructure and composition of the various coatings used in the present study are discussed in detail in Chapter 4. Unlike in case of bulk tensile testing, for which standards on the design of specimens exist, there are no standards available for the design of micro-tensile specimens. Therefore, as part of the present research work, a finite element method (FEM)-based study was carried out for ascertaining the dimensions of the specimens. The simulation studies predicted that failure of the specimens within the gage length can be ensured only when certain correlations between the dimensional parameters are satisfied. Further, the predictions from the simulation study were validated experimentally by carrying out actual testing of specimens of various dimensions. Details on the above mentioned aspects of specimen design are provided in Chapter 5. The PtAl coatings undergo brittle fracture at lower temperatures while ductile fracture occurs at higher temperatures. Further, the coatings exhibit a scatter in the yielding behavior at temperatures in the vicinity of BDTT. Therefore, the BDTT, determined as the temperature at which yielding is first observed in the stress-strain curves, may not be representative of the PtAl coatings. In Chapter 6, a method for the precise determination of BDTT of aluminide bond coats, based on the variation in the plastic strain to fracture with temperature, has been demonstrated. The BDTT determined by the above method correlated well with the variation in fracture surface features of the coating and was found representative of these coatings. In Chapter 7, the effect of temperature and strain rate on the tensile properties of a PtAl bond coat has been evaluated. The temperature and strain rate was varied between room temperature (RT)-1100°C and 10-5 s-1-10-1 s-1, respectively. The effect of strain rate on the BDTT of the PtAl bond coat has been examined. Further, the variation in fracture surface features and mechanism of fracture with temperature and strain rate are illustrated. The micro-mechanisms of deformation and fracture in the coating at different temperature regimes have also been discussed. The coating exhibited brittle-to-ductile transition with increase in temperature at all strain rates. The BDTT was strain rate sensitive and increased significantly at higher strain rates. Above BDTT, YS and UTS of the coating decreased and its ductility increased with increase in the test temperature at all strain rates. Brittle behavior occurring in the coating at temperatures below the BDTT has been attributed to the lack of operative slip systems in the B2-NiAl phase of the coating. The onset of ductility in the coating in the vicinity of BDTT has been ascribed to generation of additional slip systems caused by climb of dislocations onto high index planes. The coating exhibited two distinct mechanisms for plastic deformation as the temperature was increased from BDTT to 1100°C. For temperatures in the range BDTT to about 100°C above it, deformation was controlled by dislocations overcoming the Peierls-Nabarro barrier. Above this temperature range, non-conservative motion of jogs by jog dragging mechanism controlled the deformation. The transition temperature for change of deformation mechanism also increased with increase in strain rate. For all strain rates, fracture in the coating at test temperatures below the BDTT, occurred by initiation of cracks in the intermediate single phase B2-NiAl layer of the coating and subsequent inside-out propagation of the cracks across the coating thickness. Ductile fracture in the coating above the BDTT was associated with micro-void formation throughout the coating. The effect of Pt content on the tensile behavior of PtAl coating, evaluated at various temperatures ranging from room temperature (RT) to 1100°C and at a nominal strain rate of 10-3 s-1, is presented in Chapter 8. Irrespective of Pt content in the coating, the variation in tensile behavior of the coating with temperature remained similar. At temperatures below BDTT, the coatings exhibited linear stress-strain response (brittle behavior) while yielding (ductile behavior) was observed at temperatures above BDTT. At any given temperature, the elastic modulus decreased while the strength increased with increase in Pt content in the coating. On the other hand, the ductility of the coating remained unaffected with Pt content. The BDTT of the coating also increased with increase in Pt content in the coating. Addition of Pt did not affect the fracture mechanism in the coating. Fracture at temperatures below BDTT was caused by nucleation of cracks at the intermediate layer and their subsequent inside-out propagation. At high temperatures, fracture occurred in a ductile manner comprising void formation, void linkage and subsequent joining with cracks. The deformation sub-structure of the coating did not get affected with Pt incorporation. Short straight dislocations were observed at temperatures below BDTT, while, curved dislocations marked by jog formation were observed at temperatures above BDTT. The factors controlling fracture stress and strength in the PtAl coatings at various temperatures have also been assessed. The overall summary of the present research study and recommendations for future studies are presented in the last chapter, i.e. Chapter 9.

This master thesis project was performed in collaboration with Scania CV AB, Engine Materials group. The purpose with the project was to investigate different ceramic TBC (Thermal Barrier Coating) thermal insulation properties inside the combustion chamber. Experimental testing was performed with a Single-Cylinder engine with TBC deposited on selected components. A dummy-valve was developed and manufactured specifically for this test in order to enable a water cooling system and to ease the testing procedure. The dummy-valve consists of a headlock, socket, valve poppet and valve shaft. Additionally, a copper ring is mounted between the cylinder head and the valve poppet to seal the system from combustion gases. Thermocouples attached to the modified valve poppet and valve shaft measured the temperature during engine test to calculate the heat flux. The TBCs consisted of three different materials: 7-8% yttrium-stabilized zirconia (8YSZ), gadolinium zirconia and lanthanum zirconia. The 8YSZ TBC was tested as standard, but also with microstructural modifications. Modifications such as pre-induced segmented cracks, nanostructured zones and sealed porosity were used. The results indicated that the heat flux of 8YSZ-standard, 8YSZ-nano and 8YSZ-segmented cracks was in level with the steel reference. In the case of 8YSZ-sealed porosity the heat flux was measured higher than the steel reference. Since 8YSZ-standard and 8YSZ-sealed porosity are deposited with the same powder it is believed that the high heat flux is caused by radiative heat transfer. The remaining samples have had some microstructural changes during engine testing. 8YSZ-nano had undergone sintering and its nanostructured zones became fewer and almost gone after engine testing leading to less heat barrier in the top coat of the TBC. However, for 8YSZ-segmented cracks and gadolinium zirconia lower heat flux was measured due to the appearance of horizontal cracks. These cracks are believed to act as internal barriers as they are orientated perpendicular to the heat flow. During long-time (5 hour) engine tests the 8YSZ-standard exhibited the same phenomena: a decrease in heat flux due to propagation of horizontal cracks. One-dimensional heat flux was not achieved and the main reason for that was caused by heating and cooling of the shafts outer surface. However, the dummy-valve system has proven to be a quick, easy and stable to perform tests with a Single-Cylinder engine. Both water-cooling and long-time engine tests were conducted with minor issues. The dummy-valve has been further developed for future tests. Changes to the valve shaft are the most remarkable: smaller diameter to reduce heat transfer and smaller pockets to ensure better thermocouple positioning. Another issue was gas leakage from the combustion chamber through the copper ring and valve poppet joint. The copper ring will be designed with a 1 mm thick track to improve sealing, hence better attachment to the valve poppet.