Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : fracture strength

Study the Effect of Glass and Carbon Fibers on the Firebrick Properties

H.A. Jaber

Engineering and Technology Journal, 2017, Volume 35, Issue 4, Pages 391-398
DOI: 10.30684/etj.35.4A.11

This work was carried out to investigate effect of glass fiber (GF) and carbon fiber (CF) on kaolin-clay firebrick properties. GF and CF are considered inorganic fibers with application of high temperatures. Kaolin clay is mixed with short GF and CF separately by different percentages (0, 0.5, 1, 1.5 and 2) wt%. Kaolin-GF and kaolin-CF mixtures were compacted by using the semi-dry pressing method. The compacted specimens were fired at different temperatures (1100, 1200 and 1300)°C. Properties which include bulk density, apparent porosity, water absorption, thermal conductivity and fracture strength were obtained from the firebrick specimens. The results show that the addition of GF has beneficial in lowering of firing temperature, and consequently accelerating the densification via enhanced grain boundary diffusivity. Increasing GF content in the firebrick mixture enhances the fracture strength due to increase amount of glassy and mullite phases. Incorporation of CF has inversely affected than GF on the firebrick properties. As the percentage of CF increased the density of firebrick decreased, and the porosity and water absorption increased.

Synthesis of B4C/YTZP Composite Powder and Studying Effect of its Addition on Mechanical Properties of B4C

Fadhil A. Chyad; Mohammed H. AL-Taie; Hussein AlaaJaber

Engineering and Technology Journal, 2014, Volume 32, Issue 5, Pages 1158-1170
DOI: 10.30684/etj.32.5A.7

In this research B4C powder have been coated with yttria stabilized tetragonal zirconia polycrystalline (YTZP) (ZrO2 – 6wt% Y2O3) by using sol-gel method in order to obtain on composite powder (B4C core/ YTZP shell, 1/1 wt%). Zirconium oxychloride (ZrOCl2.8H2O) and yttrium nitrate (Y(NO3)3.6H2O) were used as the precursors for synthesis of the YTZP compound. The coated B4C powder was then used as additive powder to B4C. It was mixed with different percentages for making ceramic–ceramic composite samples. The YTZP weight percentages added to the B4C were in the range (0–12.5) wt%. The samples sintered by using spark plasma sintering technique at 1800 and 1900°C for 5 min. Density and mechanical properties (Vickers microhardness, fracturetoughness and fracturestrength) for the sintered samples were measured. The results show that the best YTZP additions to the B4C that have good mechanical properties were ranged 5 – 7.5 wt%.

Fracture Statistics of Porcelain Ceramic: The Influence of Zirconia Additive and Sintering Temperature

Fadhil A.Chyad

Engineering and Technology Journal, 2013, Volume 31, Issue 6, Pages 1081-1091
DOI: 10.30684/etj.31.6A5

The knowledge of statistic characteristics in mechanical properties is important for designer in order to asses the reliability of the structure. Scatter characteristics of fracture strength (splitting strength) of porcelain toughened by zirconia and the effect of sintering temperature were investigated in this study. Many specimens were tested by Brazillian method to obtain the scatter data of fracture strength. The probability distribution of fracture strength is evaluated by using Weibull ddistribution function.
Fracture strength is increased with zirconia content having the highest value (43MPa) at 10 wt.% and then decreased .The same behavior was for Weibull modulus, having the highest value (39) for 10 wt.% Zirconia .
Fracture strength and Weibull modulus also affected by sintering temperature, they increased with the increasing of sintering temperature.

Study Some Physical and Mechanical Properties of Ceramic – Ceramic Fibers Composite

Fadhil Attiya Chyad

Engineering and Technology Journal, 2011, Volume 29, Issue 9, Pages 1631-1640

Zirconia fibers have been prepared by convertional method using cotton threads
impregrated in zirconium oxychloride solution ( ZrOCl2. 8H2O ). X-ray
diffraction shows the crystallinity of zirconia and optical microscopy shows the
fibers fabrication. Differnet percentage ( 2 ,4 ,8 , 10 and 12 ) of prepared zirconia
fibers mixed with ZnO powder.
All the specmen sintered at 1250 °C for 2hrs. Physical properties (density and
volume shrinkage) were measured and Mechanicl properties (Vicker ̉s
hardness,fracture strength and fracture toughness by indentation method ) were
calculated, 10% of fiber content has the maximum values for these properties for
the composite.

Preparing and Studying the Effect of HA and ZrO2 Addition on Fracture Strength of Dental Ceramic

Hussein Alaa Jaber; Sinan Salman Hamde

Engineering and Technology Journal, 2010, Volume 28, Issue 6, Pages 1209-1217

This work aims at preparing and studying the effect of hydroxyapatite (HA)
and zirconia (ZrO2) additions on some physical properties and fracture strength of
dental ceramic. In this work, dental ceramic batches have been prepared from
(80% Potash feldspar, 15% silica and 5% Duekhla kaolin). Firstly, HA was
added with different percentages (2,4,6,8,10)%wt. Secondly, both of HA
and ZrO2 have been added in percentage (5%wt) with different weight
percentages for both of HA and ZrO2 to (95%wt) of dental ceramic batch.
Mixes were semi-dry pressed under (15 MPa) load, and they were fired at
(1100°C) temperature. The results show the fracture strength of the dental
that ceramic increases with the addition of HA. The best addition of HA was
(4 %wt) because it gives the best of the physical and mechanical properties.
By the addition of HA:ZrO2 mixture, the value of fracture strength
increased more than the addition of HA alone.