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Register a new userUsing New Chemical Materials as Coating Layers for Minimizing Friction and Wear
إمكانية استخدام مواد كيميائية جديدة كطبقات تبطين للتقليل من الاحتكاك و الإهتراء و التآكل
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تم قياس و تحديد سلوك التآكل و الاحتكاك لطبقة تبطين مركّبة من مادتي الكربون و الفلور بنسب تركيب معيّنة لكلٍ منها. تم رش طبقة التبطين هذه حرارياً على قرص مصنوع من حديد الصب ( فونت ). تم إجراء الانزلاق بين مسامير أسطوانية مصنوعة من مواد تبطين مكابح عضوية و الأقراص المطلية ( المغلّفة ) و غير المطلية. تم تحديد خواص مواد التبطين بعد قياس قيم القساوة و المسامية و مقاومة التآكل فيها. تم اختبار خواص مقاومة التآكل في طبقة التبطين اعتماداً على عملية تعريضها لمادة Nacl بنسبة صغيرة لمدة تزيد عن مائة و خمسين ساعة. تميزّت طبقة التبطين بأفضل مقاومة تآكل، تم إجراء اختبارات قياس قيم التآكل و الاحتكاك عند قيم ضغط تماس متفاوتة مابين (1.5MPa ÷ 7MPa) و بسرعة انزلاق 1m/sec و3m/sec.
This study deals with the friction and wear behavior of coating layers (fluoride and Graphite).The coatings are thermally sprayed on cast iron disks. Sliding is performed between cylindrical pins manufactured from organic brake linings and the coated and uncoated disks. The coatings are characterized by measuring their hardness, porosity, and corrosion resistance. The corrosion resistance of the coating is tested by exposure to Nacl for 150 hours; the coating layer has had the best corrosion resistance. The friction and wear tests are conducted under contact pressures of (1.5 MPa to 7 MPa) and sliding speeds of 1 and 3 m/sec.
References used
M.G. Jacko , Physical and chemical Changes of organic disc Pads service , wear 1978, 163-175
R.C. Tucker , ASM Handbook : Surface Engineering vol.5 , ASM International, Materials Park , OH , 1992 , Page: 497-509
Koaf.H. , Leea c.y. , Koac.J. ,chuT.c. ,carbon , Blaise Pascap,France,2005, 559-565
BHARAT Bhushan , B.K. Gupta , Handbook of Tribology : Materials, Coatings , and Surface theatments , McGraw – Hill , New York 1991,Page: 59-60
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The use of composite materials, and modern technology of plasma
spraying has provided a possibility to obtain a coating with very special
properties. Owing to physics- chimecs changes, changeable valence, low
thermodynamic strength for Ferro-oxide
s the coating, which made from
Ferro oxide composite, has very high specifications investment, and
provides protection for machines which work in difficult circumstances.
Ferro oxide composites behavior, during spraying, studies shows that
changes which took place in these materials are similar to those which
happened during sintering. An influence of plasma generator current
intensity has been studied on microhardness of forming phases, on phases
structure propositions, and on porosity. Microhardness increase when
current intensity was increased, while porosity is decreased.
Wear resistance has also been studied for this post in both, dry and wet
(oily) friction circumstances. Comparable with other materials it has been
found that Ferro oxide materials had a high resistance for wear and a low
friction coefficient.
It is also important that when selecting the spraying materials, to
determine requirements which we need from coating and to analyze its
investment circumstances on specific elements of machines to obtain a
high investment properties coating.
For voice assistants like Alexa, Google Assistant, and Siri, correctly interpreting users' intentions is of utmost importance. However, users sometimes experience friction with these assistants, caused by errors from different system components or us
er errors such as slips of the tongue. Users tend to rephrase their queries until they get a satisfactory response. Rephrase detection is used to identify the rephrases and has long been treated as a task with pairwise input, which does not fully utilize the contextual information (e.g. users' implicit feedback). To this end, we propose a contextual rephrase detection model ContReph to automatically identify rephrases from multi-turn dialogues. We showcase how to leverage the dialogue context and user-agent interaction signals, including the user's implicit feedback and the time gap between different turns, which can help significantly outperform the pairwise rephrase detection models.
This research aims to facilitate the operation of machining alloyed steel ,which contains specific ratios of nickel, chromium, magnesia, titanium and copper, through three-direction compressed cooling by,
liquid mixture. The mixture is composed of p
ressed water, pressed air, oil, salt and sulfur.
Compressed mixture was used previously but only in one direction. This work uses ternary directions vertical, horizontal and parallel to axis of work piece, which reduces the cost of expensive equipment.
The research studies the reduction in the values of cutting forces and friction factor. In ordinary machining the chips was continuous but our method it is discontinuous. The cutting tools life was increased. the effect of the nozzle diameter was also studied on the friction factor and effect of the angleγ on the cutting forces and friction factor was investigated.
This research was aimed to study a gross chemical composition of Avocado fruits
and seeds, and to known physicochemical characteristics of its oil, and its fatly acid
composition.
The data indicated that its fruits contained (12.4%) oil , while se
eds contained lower
amounts of oil which reached (1.92%) dry weight basis , and the moisture content of seeds
reached (%52.5) , and acid value reached ( 1.6and4.3 mg KOH/g) at fruit and seed oils
respectively , Avocado fruits oil contained (77.77%) unsaturated fatly acid , and (21.77%)
saturated , and iodine value obtained in our study ( 77-84 g I/100 g) of fruits oil and
( 45.78 g I/100 g) of seeds oil confirming the unsaturated nature of these oils.
Also Avocado fruits and seeds oil possessed a low peroxide value comparison others
(3.71 , 2.2 Meq/kg oil) respectively ,
The data also indicated that its seeds contained (52.5%) moisture , (7.45%) grude
fibers ,(8.53%) sugars , (4.69%) pure protein , (2.34%) ash , and high percentage of starch
(59.3%) dry weight basis .
A morphological , anatomical and chemical study was carried out on Salvia viridis
L. (Lamiaceae) . The results showed presence of two types of trichomes :
- Glandular hairs with four or eight celled globular heads or with oval heads .
- Eglandular
hairs which are unicellular or multicellular , in addition to presence of
candle shaped eglandular hairs .
The palynological study revealed that the pollen grains were prolate and they had six
germination lines , exine appeared reticulate .
The extraction of volatile oils have been done by dry evaporation using GC/MS
technique , chromatographic analysis of these extracts have showed the presence of
complex of carboxylic acids , hydrocarbons , terpenes , esters and aldehydes .
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