Theoretical model for prediction of laser sealed advanced ceramic coatings dimensions

العناوين الأخرى

نموذج رياضي للتنبؤ بأبعاد الصهر للمواد السراميكية المتقدمة المعاملة بالليزر

مقدم أطروحة جامعية

al-Tamimi, Ikhlas Idan Qadir

مشرف أطروحة جامعية

Mahmud, Adil Khalil
Hasan, Shakir Sakran

أعضاء اللجنة

Hashim, Safa
al-Amiri, Salam
Hadi, Intisar Abd al-Rida

الجامعة

الجامعة التكنولوجية

الكلية

قسم هندسة المكائن و المعدات

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2007

الملخص الإنجليزي

For industrial applications of laser sealing processing (laser surface melting), it is necessary to know the dimensions (width and depth) of the laser sealed tracks under various operating conditions of coating thickness and material properties.

The problem is that there is no exact measuring device that can follow the behavior of surface temperature (sensors are slow compared with laser) and with the difficulties in experimental work and the high costs of advanced ceramic materials it will be necessary to predict theoretically the results of laser sealing (melting) process. This prediction was in two ways:-Theoretical (using heat transfer equations to build a case study of the problem and solve it by constructing a computer program “Visual BASIC “, based on Brugger model) to predict the sealed track dimensions , and coverage rate results.

The second way is the Finite- Element method (building a simulated model and record the dimensions of sealed track, temperature distribution and thermal stresses).

The results of these methods are compared with experimental work of laser sealed partially stabilized zirconia as advanced thermal barrier coating which shows a more than 80% convergent in sealing depth results with power densities (141.54, 198.154 and 133.23 W/mm2) but 73.9% convergent with power density58.59 W/mm2, while a 70% convergent in calculating sealing width with powers (141.54, 198.154 and 133.23 W/mm2) but a 66% convergent with power 58.59 W/mm2. The predicted results showed a good agreement (ranged from 60% to 95%) with experimental results specially in the prediction of sealing depth which is less affected by surrounding environment in contrast to the melting width which is severely affected by laser parameters (power density, beam diameter, laser mode) and the properties of advanced ceramic coating material such as:- (reflectivity, absorbtivity and thermal conductivity).

The thermal barrier coating (TBC) temperature was recorded and sometimes exeed the evaporative point of TBC.

It can be seen that the heat affected area by laser beam is almost equal to the diameter of laser beam.

Also this research gives an insight to the behavior of temperature distribution on the substrate.

The resulting thermal stresses induced due to rapid heating and cooling of the TBC were calculated. A compressive stress induced in the top layer of ceramic coatings and a tensile stresses induced in the interface between the ceramic coating and the bond coat layer.

التخصصات الرئيسية

هندسة المواد والمعادن

عدد الصفحات

107

قائمة المحتويات

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-749220