Influence of laser surface hardening on corrosion properties of Al-Zn-Si cast alloy

This work is focused on the effect of the laser surface treatment (laser power 50 and 80 W) on microstructure and corrosion properties of self-hardened AlZn10Si8Mg cast alloy used for engine and vehicle constructions. The electrochemical impedance spectroscopy (EIS) technique and Nyquist plots in a 1M NaCl test solution at 20 °C were carried out. A detailed corrosion study showed that corrosion resistance samples with laser layer were marginally less; probably the presence of chloride ions significantly damaged the Al2O3 film and caused the formation of NaAlO2

Influence of laser surface hardening on corrosion properties of Al-Zn-Si cast alloy

This work is focused on the effect of the laser surface treatment (laser power 50 and 80 W) on microstructure and corrosion properties of self-hardened AlZn10Si8Mg cast alloy used for engine and vehicle constructions. The electrochemical impedance spectroscopy (EIS) technique and Nyquist plots in a 1M NaCl test solution at 20 °C were carried out. A detailed corrosion study showed that corrosion resistance samples with laser layer were marginally less; probably the presence of chloride ions significantly damaged the Al2O3 film and caused the formation of NaAlO2

Possibilities of Fe-RICH phases elimination with using heat treatment in secondary Al-Si-Cu cast alloy

The mechanical properties of Al-Si-Cu cast alloy are strongly dependent upon the morphologies, type and distribution of the second phases. The skeleton like – Al15(FeMn) 3Si2 and needles - Al5FeSi phases were observed in experimental material AlSi9Cu3. The Fe-rich phases morphology was affected with applying two types of heat treatment; T4 and T6, which caused positive changes of mechanical properties especially ultimate tensile strength; gives that for as cast state was Rm = 211 MPa, than at optimum T4 (515 °C/ 4 hours) was Rm = 273 MPa and at optimum T6 (515 °C/ 4 hours with artificial aging 170 °C/ 16 hours) was Rm = 311 MPa

ORAL HEALTH STATUS IN PATIENTS WITH CARDIOVASCULAR DISEASE

Introduction, aim: Cardiovascular diseases are some of the most common health and society problems in the present population. Oral health is considered as a risk factor in the development of cardiovascular diseases. Contemporary knowledge of the metastatic opportunistic infection of oral etiology is widely known. Methods: This article brings evaluation of oral health in 187 patients undergoing cardiovascular surgery. Patients were examined at the Department of Stomatology, Faculty of Medicine and University Hospital in Pilsen, Charles University during years 2015-2018. Advanced information about the detection of oral bacteria on pathologically changed heart valves are added. The results of the prospective epidemiological study brought information about the neglected state of oral health of these patients; more than half of the examined patients (64.17%) were at risk of metastatic opportunistic infection of oral etiology. The results of the experimental part of the study confirmed the presence of bacterial genetic information on extracted pathologically changed heart valves in 21 samples. Conclusion: The thesis emphasizes the insufficient state of oral health leading to a higher risk of metastatic opportunistic infection in patients with cardiovascular disease. Oral health should not be underestimated in patient prior to the cardiovascular surgery

The Evaluation of the Occurrence of the Oral Focal Infection. The Group of 278 Patients

Introduction and aims: Focal infection is defined as a type of disease when the chronic disease arises in the remote organ or tissue from the primary locus of the infection. The aim of this retrospective study is to assess the prevalence of oral focal infection in 278 patients sent with a request to define a possible risk of local infection in the oral cavity. Methods: In the medical documentation, we have found 278 patients referred to the Dental Clinic, University Hospital in Pilsen since 2011, for the exclusion of oral focal infection. The patients' oral health status, the presence of the teeth suspected of dental focal infection, the need for conservative, periodontal and oral surgery rehabilitation was evaluated. Results: The group of 278 patients was divided into two groups. Group A consisted of 19 patients who were referred to the dental clinic with a request for confirmation or exclusion of oral focal infection as a source of the patient`s disease. Group B consisted of 259 patients referred to the dental clinic within the preoperative medical assessment. On the basis of the documentation, the state of teeth and periodontium and the need for subsequent therapy was retrospectively assessed.In Group A, rehabilitated dentition was observed in only three patients (15.8%). Occurrence of focal infection of oral origin was diagnosed in 15 patients (78.9%), 12 patients were recommended to extract the teeth. Conservative periodontal treatment was required in for 16 patients (84.2%).In Group B, rehabilitated teeth were found in 35 patients (13.5%), focal infection of oral origin was found in 145 patients (56%). In 129 patients (49.8%) at least one tooth extraction was necessary. Conservative treatment of periodontium was necessary in 175 patients (67.6%). Conclusion: Our study evaluated that the oral health status of the majority of patients investigated for possible occurrence of infection in the oral cavity was insufficient. The results showed that it is necessary to raise awareness among the population about the importance of the impact of oral health on overall health

Study of the Properties of the AlSi9Cu3 Alloy Depending on the Ratio of Returnable Material in the Batch

Recycling of aluminium returnable material through its reuse is now an essential component of the production of aluminium alloy castings. The main goal is to find a suitable ratio of the primary alloy and the returnable material in the batch, thus determining the right compromise between the price and the quality of the casting. Experimental alloys were evaluated by thermal analysis, combination of structural analytical techniques and selected mechanical properties. The alloys were also subjected to tearing susceptibility testing. The increase in the returnable material amount resulted in changes in the alloy properties at the first increase in volume to 20%. After exceeding the balanced ratio (50:50), there was considerable degradation of the microstructure, failure to achieve the minimum values of some mechanical properties required by the standard, and the alloy showed increased susceptibility to tearing

Identyfikacja i analiza faz międzymetalicznych w utwardzanych przez starzenie stopach odlewniczych AlSi9Cu3 z recyklingu

Purpose: The influence of age-hardening solution treatment at temperature 515 degrees centigrade with holding time 4 hours, water quenching at 40 degrees centigrade and artificial aging by different temperature 130, 150, 170 and 210 degrees centigrade with different holding time 2, 4, 8, 16 and 32 hours on changes in morphology of Fe-rich Al15(FeMn)3Si2 and Cu-rich (Al2Cu, Al-Al2Cu-Si) intermetallic phases in recycled AlSi9Cu3 cast alloy. Material/Methods: Recycled (secondary) AlSi9Cu3 cast alloy is used especially in automotive industry (dynamic exposed cast, engine parts, cylinder heads, pistons and so on). Microstructure was observed using a combination of different analytical techniques (scanning electron microscopy upon standard and deep etching and energy dispersive X-ray analysis – EDX) which have been used for the identification of the various phases. Quantitative study of changes in morphology of phases was carried out using Image Analyzer software NIS-Elements. The mechanical properties (Brinell hardness and tensile strength) were measured in line with STN EN ISO. Results/Conclusion: Age-hardening led to changes in microstructure include the spheroidization of eutectic silicon, gradual disintegration, shortening and thinning of Fe-rich intermetallic phases and Al-Al2Cu-Si phases were fragmented, dissolved and redistributed within alpha-matrix. These changes led to increase in the hardness and tensile strength in the alloy.Cel: Badanie wpływu utwardzania przez starzenie przesycanie w temperaturze 515 stopni Celsjusza z czasem przetrzymywania 4 godz., hartowanie wodne w 40 stopniach Celsjusza, starzenie przyspieszone w różnych temperaturach: 130, 150, 170 i 210 stopni Celsjusza, przy czasach przetrzymywania: 2, 4, 8, 16 i 32 godziny na zmiany w morfologii stopów odlewniczych AlSi9Cu3 z recyklingu wzbogaconych żelazem (Al15(FeMn)3Si2) lub miedzią (Al2Cu, Al-Al2Cu-Si). Materiał i metody: Pochodzący z recyklingu (wtórny) stop odlewniczy aluminium AlSi9Cu3 jest powszechnie używany, zwłaszcza w przemyśle motoryzacyjnym (dynamiczne, odkryte odlewy, części silnika, głowice cylindrów, tłoki itp.). Mikrostrukturę odlewów badano stosując kombinację różnych technik analitycznych (elektronowa mikroskopia skaningowa w połączeniu z analizą rentgenowską z dyspersją energii (EDX), standardową i z głebokim wytrawianiem), co pozwoliło identyfikować różne fazy międzymetaliczne. Ocena ilościowa zmian w morfologii tych faz została przeprowadzona przy wykorzystaniu oprogramowania analizatora obrazów (Image Analyzer NIS-Elements). Właściwości mechaniczne (twardość w skali Brinella i wytrzymałość na rozciaganie) były mierzone zgodnie z normą STN EN ISO. Wyniki i wnioski: Utwardzanie przez starzenie prowadzi do zmian w mikrostrukturze, które polegają na sferoidyzacji krzemu eutektycznego, stopniowej dezintegracji, skracaniu i ścienianiu faz międzymetalicznych wzbogaconych żelazem. Fazy Al-Al2Cu-Si podlegały fragmentacji, zostały rozpuszczone i redystrybuowane w osnowie stopu. Zmiany te prowadzą do wzrostu twardości stopu i jego wytrzymałości na rozciąganie

Poor Dental Health as a Risk Faktor for Preterm Low Birth Weight Delivery

Introduction and aims: Poor dental health and chronic periodontitis may be an independent risk factor for pregnancy or delivery complications. The aim of this study was to investigate and compare dental health status of pregnant women with risk and physiologic pregnancy and of low-birth-weight baby's mothers. Materials and methods: The study included 81 pregnant women in the third trimester (group A), 30 mothers (child birth weight ≤ 1500 g) (group B) and 61 women with a physiologic pregnancy (group C).The age, general health status, DMFT, CPI, PBI indices and the need of dental treatment have been recorded in all women. Results: The average age of women with risk pregnancy was 34.7 years. The average age of women in both groups (B and C) was 32 years. The average value of DMF amounted to 11.3, 11.6 and 12.8 in women of C, B and A groups respectively. Untreated caries occurred in 107 women [62 women with risk pregnancy (76.5%), 13 mothers (34.2%) and 32 women with physiologic pregnancy (52.5%)]. The women with a physiologic pregnancy had significantly lower PBI score than women in groups A and B (p = 0.0194, p= 0.0199). The need of hygienic briefing and periodontal treatment (CPI ≥ 1) was found totally in 178 women [81 women (100%) with risk pregnancy, 37 mothers (97.4%) and 60 women (98%) with a physiologic pregnancy]. Periodontal pockets 3.5-5.5 mm (CPI = 3) were found in 28 women [16 women (19.75%) with risk pregnancy, six mothers (15.79%) and six women (9.84%) with physiologic pregnancy]. Three women had periodontal pockets deeper than 5.5 mm, two of them were those with risk pregnancy (2.47%) and one with physiologic pregnancy (1.64%). Periodontal pockets were detected in only 10 of 52 women, that delivered low-birth-weight babies. Conclusion: The study has not confirmed influence periodontal pockets on the preterm delivery but confirmed the need of increased attention to periodontal tissues and oral hygiene during preventive dental appointments in pregnant women

Factors Affecting Food Purchases in Vysočina Region with Focus on Regional Food

The article presents the results of a research study that analyses chosen factors that affect food purchases in Vysočina Region with focus on a regional food. The quantitative research, conducted in 2015 in each district of Vysočina Region (Jihlava, Žďár nad Sázavou, Třebíč, Havlíčkův Brod and Pelhřimov), analysed the opinions of 819 respondents. They were selected by quota sampling methods according to gender. Data have been processed with correspondence analysis; the results show that brand and price are significant factors that influence consumers in Vysočina Region when they buy food, the labels on the food packaging do not seem to be a strong signal of quality. Statistical tests based on contingency tables proved that regional food is strongly preferred by women and consumers over 65 years old

The Influence of the Structure on the Fatigue Properties of Al-Mg Cast Alloy

The article will be focused on monitoring the influence of the structure on the fatigue properties of aluminium alloys for the casting of type Al-Mg. As an experimental material were used aluminium alloys EN AC 51200 and EN AC 51500, supplied in a cast state without a heat treatment. They were produced by the continuous casting method. These alloys were selected on the basis of the chemical composition, where the content of most alloying elements is comparable, only in the case of the concentration of magnesium are these alloys significantly different. Fatigue properties of aluminium alloys were tested by three-point bending cyclic loading. The fracture surface of the testing sample was examined using scanning electron microscopy (SEM), where samples were observed on various stages of the fatigue process, their characteristics and differences of fracture surfaces