Noise Induced Hearing Loss (NIHL) is a sensorineural hearing loss resulting from excessive noise exposure (von Geirke, 1975). In New Zealand the Department of Labour stipulates that employees must not be exposed to more than an eight-hour equivalent continuous A-weighted sound pressure level (LAeq,8h) of 85 dB(A) or a peak sound pressure level (Lpeak) of 140 dB(A). Sandblasting is a process, whereby an abrasive is mixed with air at high pressures and exposes the operators to excessive noise (Blair, 1975). The protective equipment currently worn is a closed respirator system consisting of a helmet and cape, overseas research indicates noise levels inside the helmet are above the allowable levels (Blair, 1975; Environmental Medicine Unit, 1998; Irving, 1995; Patel and Irvings, 1999; Price and Whitaker, 1986 and Sussel 1992). There is disagreement in the literature as to the contribution of the noise created by the respirator system to the total noise exposure (Blair, 1975; Environmental Medicine Unit report, 1998; Irving, 1995 and Price and Whitaker, 1986). In some blasting sites additional hearing protection such as foam insert earplugs and/or earmuffs are worn in conjunction with the helmet. No research could be found investigating the resulting attenuation these combinations provide. It is well reported in the literature that the combined attenuation is more complex than the simple sum of the two components attenuation (Abel & Armstrong, 1991; Abel & Odell, 2006; Behar, 1990; Berger, 1983; Damongeot, Lataye & Kusy, 1989). The aims of the current study were to investigate noise levels during blasting inside booths and the operators’ helmets at two sites in New Zealand. The attenuation provided by the helmet alone and in combination with earmuffs was investigated in the laboratory. The contribution of the respirator airflow to the total noise exposure was also investigated. Finally the measured combined attenuation was compared to that calculated using three methods from the literature. Findings indicate that noise levels in blasting booths and inside operators’ helmets are above allowable levels. Laboratory findings indicate that the use of earmuffs in conjunction with the helmet increases the attenuation provided, therefore decreasing the risk of NIHL and that noise from the respirator airflow does not contribute to the total noise inside the helmet. The combined attenuation calculated from two methods in the literature was inaccurate while one was close. The findings, recommendations, limitations of the study and areas for further research are discussed.

The diploma thesis clarifies the issue of creating inscriptions on stone slabs. It describes some types of sensors, actuators, their physical principles and possibilities of their use. The work mentions the limitations and specifics of sandblasting, design solutions and implementation of equipment for patternless sandblasting.The functionality of the device is demonstrated and verified on illustrative examples.

OBJECTIVES: To evaluate accelerated and real time aging effect on microstructure and mechanical properties of different types of zirconia’s with various surface treatments. METHODS: In this in-vitro study 830 discs were prepared from four Y-TZP based materials. These materials were TZ-3YSB-E, ZPex®, ZPex® Smile (Tosoh Corporation, Japan), and Cercon®xt extra translucent zirconia (Dentsply-Sirona). Final dimensions of each specimen disc were about 15 mm in diameter and 1.5 mm thick. An accelerated aging process for 5, 24, and 168 hours of steam aging at 134°C under a pressure of 0.2 MPa was applied to the specimens. Real time aging was performed for one year in normal saline solution at 37°C in an incubator. Sandblasting was performed using a PrepStar® system with Al2O3 50μm particle size at pressure of 60 psi, rate 4.2 gram/minute. Grinding with a Buehler AutoMet 250 was performed using a 240 μm diamond disc with a 0.0034 kg/mm2 load and speed of 120 rpm for two minutes. Bruker D8 advance diffractometer was used for the acquisition of X-ray diffraction (XRD) spectrum. Biaxial flexural strength was determined using a ball-on-three-balls configuration in a universal testing machine. Scanning Electron Microscopy (SEM) was used to examine the sample's surface topography. RESULTS: The results of this study show that the zirconia materials with smaller grain size have higher flexural strength. Sandblasting and grinding treatment increases the tensile flexural strength of TZ-3YSB-E and ZPex® compared to the controlled group of the same material. XRD analysis shows that TZ-3YSB-E at room temperature does not have any monoclinic phase before surface treatment and it increased after aging, sandblasting and grinding. Cercon®xt has the highest amount of cubic phase and it increases with surface treatment. CONCLUSION: Sandblasting surface treatment should not be applied to all types of zirconia and it has to be material specific. Within the scope of this study, accelerated aging process did not affect the grain size of all materials control groups. The smaller grain size of zirconia is correlated to higher flexural strength of the material. The smaller amount of cubic phase present is correlated to higher biaxial flexural strength.

OBJECTIVES: The purpose of this study was to investigate the influence of saliva contamination and subsequent surface treatments on the shear bond strength of two different resin cements to zirconia. MATERIALS AND METHODS: One hundred sintered zirconia specimens were divided into two groups (n=50), one for each resin cement to be tested. Each group was divided into five sub-groups (n=10) based on the surface treatment the zirconia plates were going to receive; namely control (CL), saliva contaminated (SC), water washed (WW), Ivoclean (IC) and air abrasion (AA). In the control group, no contamination or surface treatment was performed. Specimen surfaces of the rest of the experimental groups were contaminated with saliva, and then submitted to drying with air only (SC); washed with water (WW); treated with Ivoclean cleaning paste (IC); or sandblasted with aluminum oxide particles (Al2O3) (AA). Multilink Automix (MA) and RelyX Ultimate (RU) resin cement cylinders were made and bonded to conditioned zirconia specimens using the Ultradent jig method. All bonded specimens were placed inside glass containers filled with deionized water inside an incubator at 37 °C for 24 h. After 24 h, the shear bond strength of the bonded specimens was tested using an Instron Universal Testing Machine with a crosshead speed of 0.5 mm/minutes. Statistical analysis was performed by ANOVA and data were analyzed with Tukey-Kramer HSD multiple comparison tests at the 0.05 level of significance. RESULTS: Within the limitations of this in vitro study, it was determined that saliva contamination significantly reduced resin bond strengths to zirconia ceramic. Airborne-particle abrasion was the most effective cleaning and surface treatment. It significantly increased the shear bond strength of (MA) (13.73 ± 1.39 MPa) and (RU) (6.34± 0.8 MPa). The IC was effective in removing saliva contamination and enhancing the resin bond strength of (MA) (10.9 ± 1.28 MPa) and (RU) (3.1± 0.16MPa). Water did not remove saliva contamination and did not improve (RU) bond strength to zirconia (1.73 ± 0.25 MPa). There was no significant difference (p>0.05) between the shear bond strengths of (MA), water washing (4.7± 0.64 MPa), and control groups (4.9± 0.27 MPa). CONCLUSIONS: If contamination occurs, a surface treatment is required to guarantee an adequate interaction between the resin cement and the zirconia surface. Airborne-particle abrasion and Ivoclean surface treatments are effective in removing saliva contamination and enhancing the resin bond strength. Washing with water alone did not improve resin bond strength.

In this diploma thesis, we propose a prototype of a dental sandblasting machine. This machine’s drawing is composed using a CAD program, which helped with checking the assembly ability. Later in this work, we discuss the design of each component and chosen technologies for production. We chose to describe in detail and prototype using the CNC machine the “exit jet” component, which combines an abrasive and air with water. The main outputs of this work are the prototype of this component and its technical rating and the technical-economical rating of the whole proposed design of the machine.

O estudo teve o objetivo de avaliar a resistência adesiva e a degradação da interface entre uma cerâmica tratada com laser e cimentos resinosos. Sessenta e quatro blocos cerâmicos foram distribuídos em 16 grupos distribuídos de acordo com os fatores em estudo: tratamento da superfície interna da cerâmica: Oxido de Alumínio (Ox), Rocatec (R), Laser de Nd:YAG 141,54 J/cm2 (Nd) e Laser de Nd:YAG + Rocatec (NdR); cimentos resinosos: Panavia F (Kuraray) e Relyx Unicem (3M ESPE); e método de envelhecimento: água destilada (W) e hipoclorito de sódio 10% (H). Após os procedimentos de cimentação e corte dos blocos, metade dos palitos foi armazenada em solução de hipoclorito de sódio 10% para simular envelhecimento in vitro. A resistência de união foi avaliada através do ensaio de microtração (0,5 mm/min) e os padrões de fratura foram classificados em adesivo, coesivo ou misto. Blocos cerâmicos adionciais foram confeccionados e analisados em Microscopia Eletrônica de Varredura e em Microscópio de Força Atômica para verificação dos padrões gerados pelos tratamentos. Os grupos tratados com laser de Nd:YAG apresentaram os maiores valores de resistência de união. Para os grupos cimentados com Panavia F, os valores de resistência de união foram: OxW: 27,71±6,3; RW: 35,67±5,13; NdW: 42,49±6,8; NdRW: 37,41±4,76; OxH: 22,27±6,05; RH: 27,49±8,83; NdH: 32,24±6,94; NdRH: 31,75±7,77. Para os grupos com RelyX Unicem: OxW: 26,74±6,34; RW: 35,07±6,02; NdW: 41,05±7,71; NdRW: 33,85±6,03; OxH: 22,77±7,37; RH: 27,84±6,26; NdH: 36,42±5,08; NdRH: 27,6±5,8. Pode-se concluir que o laser de Nd:YAG foi o tratamento mais efetivo, seguido da associação entre o laser de Nd:YAG+Rocatec, Rocatec e jateamento com Al2O3. Os cimentos testados apresentam comportamentos similares. O envelhecimento in vitro com hipoclorito de sódio diminuiu os valores de resistência de união. / The aim of this study was to evaluate the influence of different surface treatments on resistance to degradation between In-Ceram Alumina and two resin-based cements. Sixteen experimental groups were formed according to ceramic treatment: Sandblasting (S), Rocatec System (R), Nd:YAG Laser (Nd), Nd:YAG Laser plus Rocatec System (NR); luting cement: Panavia F (Kuraray) or Relyx Unicem (3M ESPE); and aging method: water (W) or sodium hypochlorite (H). Sixty four In-Ceram Alumina blocks (10x10x6mm) received four surface treatments: Al2O3 sandblasting; Al2O3 sandblasting + Rocatec Plus; Al2O3 sandblasting + Nd:YAG Lase; Al2O3 sandblasting + Nd:YAG Laser + Rocatec Plus. Each conditioned ceramic block was bonded to a composite block using a resin cement system. After 24h storage time, the blocks were sectioned to obtain sticks with cross-sectional area of 1.0mm2. The specimens were loaded to failure in a universal testing machine at a crosshead speed of 0.5mm/min. The fractured surface morphology of the debonded specimens was observed (40X) to evaluate the fracture pattern. Failure modes were classified as adhesive, cohesive in ceramic, cohesive in resin cement and mixed. The ceramic treatment and the aging method significantly affected the microtensile bond strength. Nd:YAG surface treatment resulted in the best bond strength values. To groups luted with Panavia F cement the microtensile bond strength values were: SW: 27,71±6,3; RW: 35,67±5,13; NdW: 42,49±6,8; NdRW: 37,41±4,76; SH: 22,27±6,05; RH: 27,49±8,83; NdH: 32,24±6,94; NdRH: 31,75±7,77. To groups luted with RelyX cement: SW: 26,74±6,34; RW: 35,07±6,02; NdW: 41,05±7,71; NdRW: 33,85±6,03; SH: 22,77±7,37; RH: 27,84±6,26; NdH: 36,42±5,08; NdRH: 27,6±5,8. Nd:YAG laser was the most effective surface treatment, followed by Nd:YAG+Rocatec, Rocatec and Al2O3 sandblasting. Resin cements presented similar behaviors in spite of aging. NaOCl 12h-immersion decreased Bond strength values.

O estudo teve o objetivo de avaliar a resistência adesiva e a degradação da interface entre uma cerâmica tratada com laser e cimentos resinosos. Sessenta e quatro blocos cerâmicos foram distribuídos em 16 grupos distribuídos de acordo com os fatores em estudo: tratamento da superfície interna da cerâmica: Oxido de Alumínio (Ox), Rocatec (R), Laser de Nd:YAG 141,54 J/cm2 (Nd) e Laser de Nd:YAG + Rocatec (NdR); cimentos resinosos: Panavia F (Kuraray) e Relyx Unicem (3M ESPE); e método de envelhecimento: água destilada (W) e hipoclorito de sódio 10% (H). Após os procedimentos de cimentação e corte dos blocos, metade dos palitos foi armazenada em solução de hipoclorito de sódio 10% para simular envelhecimento in vitro. A resistência de união foi avaliada através do ensaio de microtração (0,5 mm/min) e os padrões de fratura foram classificados em adesivo, coesivo ou misto. Blocos cerâmicos adionciais foram confeccionados e analisados em Microscopia Eletrônica de Varredura e em Microscópio de Força Atômica para verificação dos padrões gerados pelos tratamentos. Os grupos tratados com laser de Nd:YAG apresentaram os maiores valores de resistência de união. Para os grupos cimentados com Panavia F, os valores de resistência de união foram: OxW: 27,71±6,3; RW: 35,67±5,13; NdW: 42,49±6,8; NdRW: 37,41±4,76; OxH: 22,27±6,05; RH: 27,49±8,83; NdH: 32,24±6,94; NdRH: 31,75±7,77. Para os grupos com RelyX Unicem: OxW: 26,74±6,34; RW: 35,07±6,02; NdW: 41,05±7,71; NdRW: 33,85±6,03; OxH: 22,77±7,37; RH: 27,84±6,26; NdH: 36,42±5,08; NdRH: 27,6±5,8. Pode-se concluir que o laser de Nd:YAG foi o tratamento mais efetivo, seguido da associação entre o laser de Nd:YAG+Rocatec, Rocatec e jateamento com Al2O3. Os cimentos testados apresentam comportamentos similares. O envelhecimento in vitro com hipoclorito de sódio diminuiu os valores de resistência de união. / The aim of this study was to evaluate the influence of different surface treatments on resistance to degradation between In-Ceram Alumina and two resin-based cements. Sixteen experimental groups were formed according to ceramic treatment: Sandblasting (S), Rocatec System (R), Nd:YAG Laser (Nd), Nd:YAG Laser plus Rocatec System (NR); luting cement: Panavia F (Kuraray) or Relyx Unicem (3M ESPE); and aging method: water (W) or sodium hypochlorite (H). Sixty four In-Ceram Alumina blocks (10x10x6mm) received four surface treatments: Al2O3 sandblasting; Al2O3 sandblasting + Rocatec Plus; Al2O3 sandblasting + Nd:YAG Lase; Al2O3 sandblasting + Nd:YAG Laser + Rocatec Plus. Each conditioned ceramic block was bonded to a composite block using a resin cement system. After 24h storage time, the blocks were sectioned to obtain sticks with cross-sectional area of 1.0mm2. The specimens were loaded to failure in a universal testing machine at a crosshead speed of 0.5mm/min. The fractured surface morphology of the debonded specimens was observed (40X) to evaluate the fracture pattern. Failure modes were classified as adhesive, cohesive in ceramic, cohesive in resin cement and mixed. The ceramic treatment and the aging method significantly affected the microtensile bond strength. Nd:YAG surface treatment resulted in the best bond strength values. To groups luted with Panavia F cement the microtensile bond strength values were: SW: 27,71±6,3; RW: 35,67±5,13; NdW: 42,49±6,8; NdRW: 37,41±4,76; SH: 22,27±6,05; RH: 27,49±8,83; NdH: 32,24±6,94; NdRH: 31,75±7,77. To groups luted with RelyX cement: SW: 26,74±6,34; RW: 35,07±6,02; NdW: 41,05±7,71; NdRW: 33,85±6,03; SH: 22,77±7,37; RH: 27,84±6,26; NdH: 36,42±5,08; NdRH: 27,6±5,8. Nd:YAG laser was the most effective surface treatment, followed by Nd:YAG+Rocatec, Rocatec and Al2O3 sandblasting. Resin cements presented similar behaviors in spite of aging. NaOCl 12h-immersion decreased Bond strength values.

L’assemblage des matériaux composites thermoplastiques tel que le PEEK est l’une des problématiques majeure de l’industrie aéronautique. Actuellement, différentes techniques sont développées pour assurer l’assemblage structural de ces matériaux, tels que : le soudage, le rivetage, le boulonnage et le collage. Les enjeux industriels majeurs sont principalement, à l’heure actuelle, la conception des structures simplifiées au maximum afin de réduire les coûts de production et la réduction des consommations énergétiques. A cet effet, l’industrie aéronautique fait fréquemment appel à l’assemblage par collage en raison de nombreux avantages qu’il offre (gain de poids, distribution régulière des contraintes, absence de trous) par rapport aux autres techniques existantes. Le PEEK (PolyEtherEtherKetone), est un matériau polymère semi-cristallin thermoplastique, à hautes performances. Ce matériau est souvent utilise dans l’industrie aéronautique principalement renforce par des fibres de carbone ou de verre. Cependant, du fait du niveau élevé de sa résistance chimique l’assemblage par collage du PEEK et de ses composites nécessitent des traitements de surfaces appropries et optimises. Or, afin d’obtenir un system collé à haute performance, la problématique scientifique et technique doit être concentrée sur la jonction entre les éléments à assembler. En effet, la qualité de cette jonction est de la plus haute importance car elle doit permettre un transfert optimal des contraintes thermomécaniques lorsque l’assemblage est soumis a ses conditions d'usage. Cette étude concerne donc, l’amélioration des propriétés mécaniques (monotones et cycliques) de l’assemblage par collage PEEK/PEEK. Dans cette optique, un traitement de surface simple de mise en œuvre est proposé. Ce traitement est le sablage, qui permet la modification topographique (morphologique) de surface. La compréhension des différents phénomènes d’interaction aux interfaces intervenant dans l’amélioration du comportement mécanique du joint de colle et qui s’inscrit dans la triptyque : « Rhéologie, Physico-chimie et topographie », est l’enjeu scientifique majeur dans cette thèse. Dans un premier temps, l’influence des paramètres du traitement tels que le temps de projection, la taille des particules, sur la morphologie de surface de différents matériaux à base de PEEK a été analysée, permettant ainsi d’établir la corrélation entre les paramètres morphologiques et les mécanismes de modification topographique de surface intervenant pendant le traitement de surface. L’un des facteurs clefs pour la compréhension des mécanismes d’interaction entre l’adhésif liquide et le substrat solide est la mouillabilité. L’analyse du comportement au mouillage en fonction des différents paramètres du traitement a été réalisée. La mouillabilité des surfaces traitées est fortement affectée par la rugosité de surface créée après ce traitement. La relation entre les paramètres morphologiques et la mouillabilité a été discutée. Enfin, l’influence des paramètres du traitement par sablage sur le comportement mécanique monotone et à long terme (essais de fatigue) sur la résistance du joint colle a été étudié à l’aide d’essais de cisaillement sur éprouvettes à simple recouvrement. Ceci a conduit, à la proposition de paramètres morphologiques surfaciques spécifiques pour l’optimisation du comportement mécanique du joint de colle des matériaux composites à matrice PEEK. / One of most problematic in the aeronautical industries is the structural joining of the high performance thermoplastic composites like PEEK composites. Actually, a lot of technologies are used for joining thermoplastic composites like welding, bolting, riveting, fastening and adhesive bonding. Due to the various advantages that characterize the adhesive bonding method, such an uniform stress distribution along the joint, weight‐light and cost reduction, makes this technique more desirable to join thermoplastic composites materials compared to the other joining techniques. PEEK (PolyEtherEtherKetone) is a semi‐crystalline thermoplastic material with high performance. This material is wildly used in aeronautical industries, principally, reinforced with carbon of glass fibres. However, its high chemical resistance makes the adhesive bonding of PEEK and its composites difficult and therefore an appropriate and optimised surface treatment is necessary. In the aim to obtain a bonded system with high performance, scientific and technical problematic should be focussed on the junction between adherents. Indeed, the quality of this junction is of utmost importance because it must allow optimum transfer of thermomechanical stresses when the assembly is subject to its terms of use. Though, at this time it is well known that thermoplastic composite materials are difficult to bond with‐out surface treatment. This study, therefore, relates to the improvement of mechanical properties (monotonic and cyclic) of the adhesive bonding system PEEK / PEEK. In this context, a surface treatment, easy to implement, is proposed. This surface treatment is sandblasting, which enables surface topographic (morphological) modifications. Understanding of various phenomena of interfaces interaction involved in the improvement of the mechanical behavior of the adhesive joint and is part of the triptych "Rheology, Physico‐chemistry and topography" is the major scientific challenge in this thesis. Initially, the influence of processing parameters such as the projection time, the particle size on surface morphology of various materials based on PEEK was analysed, thus allowing establishing the correlation between morphological parameters and modification mechanisms involved during surface treatment surface. One of the key factors for understanding the mechanisms of interaction between the liquid adhesive and the solid substrate is wettability. The analysis of the wetting behavior as a function of various parameters of the treatment was performed. The wettability of treated surfaces is strongly affected by surface roughness created after this treatment. The relationship between morphological parameters and wettability was discussed. Finally, the influence of sandblasting processing parameters on the mechanical behavior in monotoning and long‐term (fatigue tests) of the adhesive joint strength was studied, using single lap shear tests specimens. This has led to the proposal of specific surface morphological parameters for the optimization of the mechanical behavior of the adhesive joint of PEEK and its composites.