Effects of Crystallization Conditions on Lead Tin Bronze Properties

2014 ◽  
Vol 880 ◽  
pp. 174-178 ◽  
Author(s):  
Nikita Martyushev ◽  
Yuriy N. Petrenko
Keyword(s):  
Impact Strength ◽  
Phase Structure ◽  
Structure Change ◽  
Structure And Properties ◽  
Casting Mold ◽  
Research Results ◽  
Tin Bronze ◽  
Cooling Speed ◽  
Crystallization Conditions ◽  
The Impact

Research results of cooling speed influence on structure and properties lead tin bronze are given in this article. Cooling speed changed by casting mold heating to various temperatures. Following the researches results it is shown that cooling speed growth leads to growth of hardness, strength on samples stretching. Decrease in cooling speed gives decrease in hardness and strength on stretching, but at the same time the impact strength of samples increases. Results of metalgraphic researches showed that such properties changes are connected with phase structure change of cast samples.

Structure and Properties of Leaded Tin Bronze under Different Crystallization Conditions

2013 ◽  
Vol 872 ◽  
pp. 89-93 ◽  
Author(s):  
Nikita Martyushev ◽  
Ilya V. Semenkov ◽  
Yuriy N. Petrenko
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Cooling Rate ◽  
Structure And Properties ◽  
Cooling Rates ◽  
Tin Bronze ◽  
Microstructure Parameters ◽  
Influence Of Crystallization ◽  
Crystallization Conditions ◽  
High Cooling Rates

The influence of crystallization conditions of leaded tin bronze on the obtained microstructure parameters is examined in the paper. Modification of crystallization conditions was realised by varying the cooling rate of the melt with preheating of the casting molds. Quantitative regularities of the influence of the cooling rate of bronze on its phase composition are presented. Data on mechanical properties of the material under investigation are also reported in the paper. It is demonstrated that high cooling rates (casting into mold at ambient temperature) enable obtaining higher mechanical properties in comparison with low cooling rates (casting into mold heated up to 800 °С).

Structure and Properties of Multicomponent Bronze Depending on the Crystallization Conditions

2015 ◽  
Vol 756 ◽  
pp. 303-307
Author(s):  
Anton Viktorovich Korchmit ◽  
N.V. Martyushev
Keyword(s):  
Liquid Phase ◽  
Impact Strength ◽  
Liquid Phase Sintering ◽  
Structure And Properties ◽  
Phase Concentration ◽  
Crystallization Conditions ◽  
Chromium Phosphate

This work presents the characteristic properties of powdered materials sintering under conditions of liquid-phase sintering. It has been established that to implement the liquid-phase sintering advantages it is necessary to do temperature research when the liquid-phase concentration does not exceed the critical one. Impact strength is the highest for the bronze, casted in a chill mould at 1220°С, and the lowest for the bronze, casted in aluminum-chromium-phosphate moulds at the same temperature.

Study on Layered Structure and Properties of PP/LLDPE Injection Molding

2012 ◽  
Vol 602-604 ◽  
pp. 685-689
Author(s):  
You Bing Li ◽  
Yan Pan ◽  
Wen Shi ◽  
Xu Ming Sheng ◽  
Bing Dai
Keyword(s):  
Impact Strength ◽  
Injection Molding ◽  
Shear Layer ◽  
Layered Structure ◽  
Preferred Orientation ◽  
Core Region ◽  
Melt Blending ◽  
Structure And Properties ◽  
The Core ◽  
The Impact

The melt blending was used to prepare the PP/LLDPE blend, and the layered structure and properties for PP/LLDPE blends were detailed explored. The addition of LLDPE was beneficial to toughen the PP injection moldings. The impact strength also improved for addtion of LLDPE and the corresponding increase percentage in impact strength was 111% for PP/LLDEPE (65/35, w/w) comapred with pure PP. SEM showed the preferred orientation of lamella obtained in shear layer and core region. WAXD curves showed the peak of (300) β-form for PP component in the skin and core region was evident and nearly disappeared in the shear layer, and the (200) peak for LLDPE component in the skin was stronger than that in the shear layer and core region. The enthalpy value calculated by DSC data increased from the core region to the skin, which indicated the crystallinity for PP/LLDPE blends increased from the core region to the skin.

scholarly journals Impact of microorganisms on mechanical properties changes of composite materials with organic filler

2021 ◽  
Author(s):  
Jarosław Szuszkiewicz
Keyword(s):  
Composite Materials ◽  
Impact Strength ◽  
Rapid Development ◽  
Fungal Spores ◽  
Polymer Materials ◽  
Sisal Fiber ◽  
Processing Temperature ◽  
Natural Conditions ◽  
Research Results ◽  
The Impact

The beginning of the XXIst century is characterized by rapid development of polymer materials, including polymer composite materials, which consist of a natural organic filler (wood flour, sawdust, cellulose fiber, flax fiber, sisal fiber) and reinforcement carrier. In case of that kind of the fillers under the influence of weathering (humidity, temperature) they might be subject to biodegradation due to effect of microorganisms, including funguses, which are responsible for degradation of natural organic fillers. In case of the low melting temperature polymers (e.g. PE-LD) the processing temperature does not entirely eliminate some of the fungal spores. The paper has presented the research results of twelve months. The development of the microorganisms in the natural conditions was examined in a pure filler (sawdust) as well as in a composite. Simultaneously, change of one of the fundamental strength properties, which is the impact strength, was being tested. For the investigated composite the PE-LD as the matrix and a sawdust mixture of pine, larch and oak were used. The sawdust formed the composite in 30 %. The research results confirmed that in the natural conditions the microorganisms development depends on weathering which varies in the time of the year. The value of the V notch impact strength changed from 12.5 kJ/m2 for the composite in initial phase to the value of 6.7 kJ/m2 after twelve months operation, which is 50 %.

Расчетные методы оценки ударной вязкости сварных элементов с трещинами

2020 ◽  
Vol 44 (3) ◽  
pp. 22-36
Author(s):  
Keyword(s):  
Stress Intensity ◽  
Impact Strength ◽  
Welded Joints ◽  
Development Process ◽  
Welded Joint ◽  
Operating Temperature ◽  
Crack Development ◽  
Heterogeneous Structure ◽  
Critical Crack Length ◽  
The Impact

Практика показывает, что для сварных конструкций, эксплуатируемых в условиях Крайнего Севера необходимо уделять внимание работоспособности сварных соединений при низких температурах. Металл сварных соединений в процессе воздействия обработки изменяет свои свойства, снижается ударная вязкость, образуется гетерогенная структура с большой степенью разнозернистости. Чтобы оценивать и иметь возможность правильно контролировать термическое воздействие и последствия сварочного процесса, требуется решить задачу аналитического определения ударной вязкости для всех зон сварного соединения. В настоящей статье представлен инженерный метод оценки ударной вязкости, применимый для любой зоны сварного соединения, в которой имеется острый или особый концентратор напряжений – трещина. Разработанный аналитический метод расчета ударной вязкости отражает качественную и количественную картину взаимосвязи структурно-механических характеристик и работы развития трещины в диапазоне температур 77…300 К. Предложенная схематизация зависимости критического коэффициента интенсивности напряжений от температуры позволила найти коэффициенты, характеризующие свойства материала, и выполнить расчеты изменения предела текучести и предела прочности от температуры эксплуатации. Построены графики зависимости работы развития трещины от температуры эксплуатации для сталей 15ГС и 17ГС, сравнение которых с экспериментальными данными показывает удовлетворительное согласование. Найдено, что при напряжениях предела выносливости отношение работы развития трещины к критической длине трещины постоянно, не зависит от температуры и для сталей 15ГС и 17ГС равно около 10. Ключевые слова: ударная вязкость, работа разрушения, коэффициент интенсивности напряжений, трещина, феррито-перлитная сталь, зона термического влияния. For welded structures under operation in the Far North, attention must be paid to the performance of welded joints at low temperatures. The properties of metal of welded joints are changed in the process of treatment, its toughness decreases, and a heterogeneous structure with a large range of different grain sizes is formed. In order to evaluate and be able to correctly control the thermal effect and the consequences of the welding process, it is necessary to solve the problem of analytical determination of impact strength for all zones of the welded joint. The paper presents an engineering method for evaluation of the impact strength applicable to any area of the welded joint in which there is a sharp or super sharp stress concentrator – a crack. The developed analytical method for calculating the impact strength reflects a qualitative and quantitative codependency of structural and mechanical characteristics and the process of crack development in the temperature range of 77–300 K. The proposed schematization of dependence of the critical coefficient of stress intensity on the temperature made it possible to find coefficients characterizing the properties of the material and to perform calculations of changes in yield strength and tensile strength on operating temperature. Graphs of the crack development process dependency on the operating temperature for 15ГС and 17ГС steels were constructed, and their comparison with experimental data displays satisfactory agreement. It was found that at endurance limit stresses, the ratio of the crack development process to the critical crack length is constant, non-dependent on temperature, and is equal to 10 for 15ГС and 17ГС steels. Keywords: impact strength, fracture work, stress intensity factor, crack, ferrite-pearlite steel, heat affected zone, steel tempering.

Impact Strength, Flexural Modulus and Wear Rate of PMMA Composites Reinforced by Eggshell Powders

2020 ◽  
Vol 38 (7A) ◽  
pp. 960-966
Author(s):  
Aseel M. Abdullah ◽  
Hussein Jaber ◽  
Hanaa A. Al-Kaisy
Keyword(s):  
Impact Strength ◽  
Wear Rate ◽  
Flexural Modulus ◽  
Matrix Material ◽  
Weight Fraction ◽  
Pure Pmma ◽  
Calcination Process ◽  
The Matrix ◽  
The Impact ◽  
Interface Bond

In the present study, the impact strength, flexural modulus, and wear rate of poly methyl methacrylate (PMMA) with eggshell powder (ESP) composites have been investigated. The PMMA used as a matrix material reinforced with ESP at two different states (including untreated eggshell powder (UTESP) and treated eggshell powder (TESP)). Both UTESP and TESP were mixed with PMMA at different weight fractions ranged from (1-5) wt.%. The results revealed that the mechanical properties of the PMMA/ESP composites were enhanced steadily with increasing eggshell contents. The samples with 5 wt.% of UTESP and TESP additions give the maximum values of impact strength, about twice the value of the pure PMMA sample. The calcination process of eggshells powders gives better properties of the PMMA samples compared with the UTESP at the same weight fraction due to improvements in the interface bond between the matrix and particles. The wear characteristics of the PMMA composites decrease by about 57% with increases the weight fraction of TESP up to 5 wt.%. The flexural modulus values are slightly enhanced by increasing of the ESP contents in the PMMA composites.

The impact of reflective writing paper on non-English major learners’ autonomy in the context of Vietnam

2013 ◽  
Vol 17 (1-2) ◽  
pp. 104-128
Author(s):  
Phan Thi Tuyet Van
Keyword(s):  
Teaching Methods ◽  
Reflective Writing ◽  
Research Results ◽  
English Major ◽  
Study Process ◽  
The Impact ◽  
Process Journal

The article aims to investigate the impact of the reflective writing paper on non- English major learners’ learning autonomy in a Vietnamese context. The data was collected by means of questionnaire, competence tests and interviews. The participants did two reflective writing papers as an intervention during the research. The research results show the possibilities for teachers to modify their teaching methods through analysis of feedback from the subjects. The findings showed that most participants appreciated the role of the reflective writing paper and they were aware of the significance of learning autonomy in their study process. Journal of NELTA, Vol. 17 No. 1-2, December 2012, Page 104-128 DOI: http://dx.doi.org/10.3126/nelta.v17i1-2.8102

Evaluation of the Aging Behavior of High Density Polyethylene in Thermal Oxidative Environment by Principal Component Analysis

2017 ◽  
Vol 727 ◽  
pp. 447-449 ◽  
Author(s):  
Jun Dai ◽  
Hua Yan ◽  
Jian Jian Yang ◽  
Jun Jun Guo
Keyword(s):  
Principal Component Analysis ◽  
Impact Strength ◽  
High Density Polyethylene ◽  
Tensile Modulus ◽  
Principal Component ◽  
Component Analysis ◽  
High Density ◽  
Aging Behavior ◽  
Data Set ◽  
The Impact

To evaluate the aging behavior of high density polyethylene (HDPE) under an artificial accelerated environment, principal component analysis (PCA) was used to establish a non-dimensional expression Z from a data set of multiple degradation parameters of HDPE. In this study, HDPE samples were exposed to the accelerated thermal oxidative environment for different time intervals up to 64 days. The results showed that the combined evaluating parameter Z was characterized by three-stage changes. The combined evaluating parameter Z increased quickly in the first 16 days of exposure and then leveled off. After 40 days, it began to increase again. Among the 10 degradation parameters, branching degree, carbonyl index and hydroxyl index are strongly associated. The tensile modulus is highly correlated with the impact strength. The tensile strength, tensile modulus and impact strength are negatively correlated with the crystallinity.

scholarly journals X-ray Shielding, Mechanical, Physical, and Water Absorption Properties of Wood/PVC Composites Containing Bismuth Oxide

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2212
Author(s):  
Worawat Poltabtim ◽  
Ekachai Wimolmala ◽  
Teerasak Markpin ◽  
Narongrit Sombatsompop ◽  
Vichai Rosarpitak ◽  
...  
Keyword(s):  
Impact Strength ◽  
Water Absorption ◽  
Attenuation Coefficient ◽  
Bismuth Oxide ◽  
Morphological Properties ◽  
Linear Attenuation Coefficient ◽  
X Rays ◽  
Equivalent Thickness ◽  
X Ray ◽  
The Impact

The potential utilization of wood/polyvinyl chloride (WPVC) composites containing an X-ray protective filler, namely bismuth oxide (Bi2O3) particles, was investigated as novel, safe, and environmentally friendly X-ray shielding materials. The wood and Bi2O3 contents used in this work varied from 20 to 40 parts per hundred parts of PVC by weight (pph) and from 0 to 25, 50, 75, and 100 pph, respectively. The study considered X-ray shielding, mechanical, density, water absorption, and morphological properties. The results showed that the overall X-ray shielding parameters, namely the linear attenuation coefficient (µ), mass attenuation coefficient (µm), and lead equivalent thickness (Pbeq), of the WPVC composites increased with increasing Bi2O3 contents but slightly decreased at higher wood contents (40 pph). Furthermore, comparative Pbeq values between the wood/PVC composites and similar commercial X-ray shielding boards indicated that the recommended Bi2O3 contents for the 20 pph (40 ph) wood/PVC composites were 35, 85, and 40 pph (40, 100, and 45 pph) for the attenuation of 60, 100, and 150-kV X-rays, respectively. In addition, the increased Bi2O3 contents in the WPVC composites enhanced the Izod impact strength, hardness (Shore D), and density, but reduced water absorption. On the other hand, the increased wood contents increased the impact strength, hardness (Shore D), and water absorption but lowered the density of the composites. The overall results suggested that the developed WPVC composites had great potential to be used as effective X-ray shielding materials with Bi2O3 acting as a suitable X-ray protective filler.

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