A pre-flashover fire is very different from a post-flashover fire. The main difference is that in a pre-flashover fire the gas temperature and the radiation temperature differ. One thing that makes it a lot different is that the thermal exposure induced by a pre-flashover fire is largely affected by the smoke gas layer. These smoke gases can be very hot and therefore they emit heat radiation to their surroundings. The theory used, to calculate the thermal exposure of a pre-flashover fire, in this thesis relies on using thermal resistances to describe the heat transfer from the smoke gases. By doing so it is possible to calculate the temperatures of the smoke gases and the surfaces in touch with the smoke gases. Another approach is to use CFD software to numerically calculate the temperatures and in this thesis the two-zone model are compared to FDS, a CFD software. The two-zone model are also compared to a reduced-scale test. The comparisons gave good results, the two-zone model produced similar results compared to re reduced-scale test and FDS. This method of calculating thermal exposure can thereby be used to evaluate evacuation safety and save a lot of calculation time compared to calculating the thermal exposure with CFD software such as FDS.

Aluminum (Al) powder metallurgy (PM) provides a cost effective and environmentally friendly means of creating lightweight, high performance, near net shape components, relative to conventional casting/die casting technology. Unfortunately, the current lack of commercially available Al alloy powder blends has hindered development in this field as a result of the limited scope of mechanical properties available; especially under elevated temperature conditions common to many automotive applications. As such, the objective of this research was to attempt to improve the versatility of current Al PM technology through the incorporation of Fe and Ni transition metal additions into an emerging Al- 4.4Cu-1.5Mg-0.2Sn alloy, as this technique is known to enhance the elevated temperature stability of wrought/cast Al alloys through the formation of stable, Fe/Ni aluminide dispersoids. Initial experimentation consisted of evaluating the feasibility of incorporating Fe and Ni both elementally and pre-alloyed, through a series of tests related to their PM processing behaviour (compressibility, sintering response) and sintered product performance (ambient tensile properties). Results confirmed that pre-alloying of the base Al powder was the most effective means of incorporating Fe and Ni as all such specimens achieved properties similar or slightly superior to the unmodified alloy. Of the pre-alloyed systems considered, that containing 1%Fe+1%Ni displayed the most desirable results in terms of mechanical performance and microstructural homogeneity of the Fe/Ni dispersoid phases present in the sintered product. Bars of the baseline system and that modified with pre-alloyed additions of 1Fe/1Ni were then sintered industrially to gain a preliminary sense of commercial viability and obtain additional specimens for elevated temperature exposure tests. Results confirmed that the sintering response, tensile properties and microstructures were essentially identical in both alloys whether they were sintered in a controlled laboratory setting or an industrial production environment. Furthermore, DSC data indicated that S (Al2CuMg)-type phases were the dominant precipitates formed during heat treatment. The effects of elevated temperature exposure were assessed in the final stage of research. Both alloys were found to exhibit comparable behaviour when exposed to the lowest (120°C) and highest (280°C) temperatures considered. Here, the alloys showed no obvious degradation at 120°C. Conversely, exposure at 280°C prompted a steady decline in yield strength for both alloys with significant precipitate coarsening noted as well. Despite these similarities, differences emerged during isochronal tests at intermediate temperatures. Here, DSC data indicated that the precipitates present in the pre-alloyed material were stable at temperatures up to 160°C while those in the unmodified alloy had begun to overage under the same exposure conditions. These differences were accompanied by increased stability in tensile yield strength for the pre-alloyed material. In all, this study has indicated that the use of Al powder pre-alloyed with Fe/Ni additions is feasible for press-and-sinter PM technology and that the sintered product exhibits improved elevated temperature stability under certain conditions.

Firefighters’ coats and pants, referred to as firefighters’ protective clothing in this research, are made of similar fabrics and often include three layers: an outer shell, a moisture barrier, and a thermal liner. Minimum requirements of firefighters’ protective clothing performance have been clearly established by various national and international standards for new clothing to ensure the reasonable safety of firefighters. However, there are no clear guidelines on the requirements for continuing performance of firefighters’ protective clothing. In general, the protection offered by firefighters’ protective clothing is expected to deteriorate over time, but it is still uncertain how destructive different exposures are and how long a piece of firefighters’ protective clothing can continue to protect a firefighter to an acceptable level. Non-destructive techniques are preferable in order to investigate how the performance of protective clothing may change with time since this allows firefighters’ protective clothing to return to service after a test. These non-destructive methods, which could be used to monitor the level of deterioration in firefighters’ protective clothing performance and to make decisions on retirement of individual pieces of protective clothing, would be extremely useful for fire departments in Canada and other countries. Thermal exposure is an important factor in ageing of firefighters’ protective clothing during firefighting operations. Outer shell and moisture barrier specimens made of common fabrics used in construction of firefighters’ protective clothing, and of different colours, were exposed to different levels of thermal exposure simulated using a cone calorimeter in single and multiple stages. Tensile strength of outer shell specimens, and tear strength, water vapour transmission rate, and water penetration pressure of moisture barrier specimens, which are critical aspects of performance of firefighters’ protective clothing, were measured. In order to explain the changes in performance after thermal exposure, the temperature profile of specimens during each thermal exposure was recorded. Furthermore, thermogravimetric analysis for each specimen material was carried out and images of the surface of specimens were obtained using scanning electron microscope. The test results demonstrated that tensile strength of outer shell specimens deteriorated faster than other aspects of performance. Two non-destructive techniques, colour measurement and near infrared spectroscopy, were implemented to correlate tensile strength of outer shell specimens with discoloration and reflectance spectrum. Two types of correlation between tensile strength and colour change were identified among the tested fabrics, depending on the initial fabric colour, which could be a basis to develop numerical models to predict tensile strength of outer shell specimens. Linear predictive equations were developed using a numerical code based on regression analysis, which correlated tensile strength with reflectance of outer shell specimens within the wavelength region of 1500-2500 nm. A three-variable model predicted tensile strength of thermally aged test specimens, the tensile strength of which were 600 N and higher, with a relative error of up to 10%. For test specimens with tensile strength of about 300 N, the relative error was 55%. The difference in error percentage was related to a gap in training data points for the model within the tensile strength range of 300 - 600 N.

The main subject of this master’s thesis was to evalute inluence of loading cycle asymmetry and long-term thermal exposure on fatigue crack growth rate in martensitic P91 and P92 steels. Experiments were carried out in Material and metallurgical research Ostrava Ltd. and their main aim was to study the influences of different loading cycle asymmetries (R = 0,1 and R = 0,6) as well as 5000 hours/600 °C (P91) respectively 5000 hours/650 °C (P92) of thermal exposure on fatigue crack growth rate.

Abstract The qualitative and quantitative characteristics of each component layer constituting the structure of organic bulk heterojunction solar cells (OSC-BHJ) contribute significantly towards its overall performance. One of the prevalent issues resulting in reduced device efficiency is due to the conformational inhomogeneities in the active and buffer layers. The mechanical stress, extended thermal exposure and presence of mutually reactive component layers etc., affects negatively on the device stability. Effective methods to address these issues will be extensively benefited by the industry since the current commercialisation of the technology is hindered owing to the lower efficiency and stability of these devices. This dissertation focuses on methods to coherently enhance the performance and longevity of the OSC-BHJ devices. The efficiency enhancements of the devices in this work were achieved through two main routes. The first route was through morphological improvement of the active layer. The second route was through boosting the electrical characteristics of hole transporting conducting polymer layer (HTL) by controlled annealing conditions. The introduction of a suitable additive in the active layer was found to reduce unfavourable phase segregation thus resulting in enhanced morphology. Further, the annealing conditions in different atmospheres (air, nitrogen and vacuum) were found to have a clear influence on the optimum functioning of the HTL in the device. Regarding the stability improvement study done in this work, a method of employing suitable interlayer was developed to effectively abate the internal degradation occurring in the device due to etching reaction on the indium tin oxide (ITO) anode by the HTL. Moreover, experimental investigations were carried out for drawing fundamental understanding of stability degenerating issues such as the influence of mechanical defects on transparent conducting metal oxide (ITO) anode on the performance of the device and heat induced degradations in the low band gap polymer-fullerene active layer. The highlight of this research is that the discovered methods are inexpensive, efficient, and easy to adopt. The results of the study could help the technology to overcome some of its limitations and accelerate its progress towards commercialisation. / Tiivistelmä Orgaanisten heteroliitosaurinkokennojen kerrosrakenteen ominaisuudet ja laatu vaikuttavat merkittävästi aurinkokennojen toiminnallisuuteen. Erityisesti rakenteelliset epähomogeenisuudet aktiivi- ja puskurikerroksissa heikentävät kennon hyötysuhdetta. Kennojen stabiilisuutta tarkasteltaessa myös mekaanisella rasituksella, pitkittyneellä lämpöaltistuksella ja materiaalien reagoinneilla keskenään kerrosten välillä, on selkeä negatiivinen vaikutus kennojen stabiilisuuteen. Orgaanisen aurinkokennoteknologian kaupallistamisen rajoitteina ovat kennojen heikko hyötysuhde ja stabiilisuus, joten menetelmät jotka tarjoavat ratkaisuja edellä mainittuihin ongelmiin, ovat erittäin tärkeitä teknologiaa kaupallistavalle teollisuudelle. Tämä väitöskirja keskittyy johdonmukaisesti selvittämään tapoja, joilla voidaan parantaa heteroliitosaurinkokennojen hyötysuhdetta ja elinikää. Hyötysuhteen tehostamiseksi valittiin kaksi eri lähestymistapaa, joista ensimmäisessä keskityttiin aktiivikerroksen morfologian parantamiseen ja toisessa aukkoja kuljettavan kerroksen sähköisten ominaisuuksien parantamiseen lämpökäsittelyprosessin avulla. Sopivan lisäaineen avulla aktiivikerroksen ei-toivottua kiteytymistä voidaan pienentää ja parantaa näin kerroksen morfologiaa. Lisäksi työssä todettiin, että lämpökäsittelyn aikaisella ympäristöolosuhteella (ilma, typpi, tyhjiö) on merkittävä vaikutus puskurikerroksen optimaaliseen toimintaan aurinkokennossa. Stabiilisuuden parantamiseksi kehitettiin välikerroksen hyödyntämiseen perustuva menetelmä, jolla voidaan tehokkaasti vähentää kennojen sisäisessä rakenteessa tapahtuvaa toiminnallisuuden heikkenemistä, joka aiheutuu aukkoja kuljettavan kerroksen syövyttävästä vaikutuksesta indiumtinaoksidi (ITO) pohjaiseen anodiin. Tämän lisäksi työssä tutkittiin kokeellisesti stabiilisuuteen heikentävästi vaikuttavia tekijöitä, kuten mekaanisen rasituksen aiheuttamia vaurioita metallioksidi (ITO) anodissa ja lämpöaltistuksesta aiheutuvia vikoja polymeeri-fullereeni rakenteeseen perustuvassa aktiivikerroksessa. Tutkimuksen keskeisin tulos on, että esitellyt keinot aurinkokennojen hyötysuhteen ja stabiilisuuden parantamiseen ovat edullisia, tehokkaita ja helppoja hyödyntää. Tulokset voivat merkittävästi edistää orgaanisten aurinkokennojen teknistä kehitystä ja kiihdyttää niiden tuloa kaupallisiksi tuotteiksi.

No description available.