Room-Temperature Strength of Sintered Silicon Nitride Subjected to High-Temperature Creep Loading

1994 ◽  
Author(s):  
Yoshizumi Nakasuji ◽  
Hiroyuki Iwasaki ◽  
Hiroaki Sakai
Keyword(s):  
Silicon Nitride ◽  
Room Temperature ◽  
Strength Degradation ◽  
Creep Tests ◽  
Second Stage ◽  
Two Stages ◽  
Creep Loading ◽  
Applied Stresses ◽  
Room Temperature Strength ◽  
Sintered Silicon

Room-temperature strength was evaluated using sintered silicon nitride crept specimens. Creep tests were performed using 4-point bending loading at 1400°C in air. The bending creep tests applied stresses from 100 to 400 MPa for 10−1 to 3×103 hours. For applied stress over 200 MPa, the room-temperature strength of the crept specimen had two stages. In the first stage the strength degraded slowly, and in the second stage the strength degraded rapidly. In the first stage, oxidation caused the strength degradation, since the degradation was similar for the different applied stresses. In the second stage, large creep deformation mainly caused the strength degradation. Early in the stage, creep induced matrix and boundary damage under the oxidation layer caused the degradation. At the end of the stage, cracks induced by creep caused the degradation.

The Influence of Heat and Two Stages Precipitation in the Process of Natural Polymer Purification from the Byproduct of Bioethanol Process Base on Empty Palm Fruit Bunch

2015 ◽  
Vol 1123 ◽  
pp. 177-181
Author(s):  
Achmad Hanafi ◽  
Harry Budiman ◽  
Fauzan Aulia
Keyword(s):  
Sulfuric Acid ◽  
Sodium Hydroxide ◽  
Room Temperature ◽  
Black Liquor ◽  
Ash Content ◽  
Natural Polymer ◽  
Palm Fruit ◽  
Second Stage ◽  
Direct Precipitation ◽  
Two Stages

The biopolymer material, lignin, was recovered from the black liquor by acidification of the black liquor using sulfuric acid. Several purification techniques were carried out to produce the high purity of lignin such as gradual precipitation of lignin from black liquor (first stage: precipitation at pH 7, second stage: precipitation at pH 2) and the diluting of crude lignin by sodium hydroxide then followed by re-precipitation at different temperature. Subsequently, the impurities of lignin product resulted from each purification techniques was determined as ash content that analyzed using temperature program furnace; and the content of lignin was investigated using spectrophotometer UV-Vis. The result showed that the content of lignin of material produced from gradual precipitation was approximately 77.6%. It was higher than the content of lignin about 3.4% of material produced from direct precipitation to pH 2. In addition, the elevating of temperature from 40 to 60°C was no considerably affect to the content of lignin in precipitate produced from re-precipitation of crude lignin solution in sodium hydroxide. Nonetheless, the content of lignin of precipitate improved 15% when the temperature of re-precipitation of crude lignin solution in sodium hydroxide was raised from room temperature to 40-60°C.

scholarly journals Temporary Shelter Simulation Towards Effectiveness Value of OTTV and Thermal Comfort

2019 ◽  
Vol 36 (3) ◽  
Author(s):  
Dyah Puspa Ayu ◽  
Budi Prayitno ◽  
Agus Hariyadi
Keyword(s):  
Thermal Comfort ◽  
Natural Disasters ◽  
Room Temperature ◽  
Human Life ◽  
Air Humidity ◽  
Value Differences ◽  
Second Stage ◽  
Thermal Transfer ◽  
A Value ◽  
Two Stages

Indonesia is prone to a variety of natural disasters, one of which is earthquakes. Earthquakes are detrimental to human life, causing among other things a loss of shelter. As such, victims of earthquakes need basic assistance in the form of shelter, which the Indonesian government provides in the transition phase of emergency responses. Several innovations in the provision of temporary shelter have arisen in terms of packaging and fast unloading. This research aimed to examine the effective value of OTTV energy (overall thermal transfer value), differences in room temperature, and thermal comfort in existing temporary shelters. OTTV values and thermal comfort are adapted to Indonesia's humid tropical climate, which has a temperature ranging 24–30°C and air humidity of 75%. Temporary shelters were simulated with Rhinoceros and Grasshopper softwares. The simulation was carried out in two stages, with the first stage simulating the temporary shelter materials and the second stage simulating according to a predetermined standard. The results concluded that the effective value of OTTV with the use of Styrofoam-based shelter gives a value of 27.63 W/m2 with a decrease of up to 4.70 W/m2 and the temperature drops to 2–3°C.

Effect of Grinding Variables on Strength of Hot Pressed Silicon Nitride

1983 ◽  
Author(s):  
R. L. Allor ◽  
R. R. Baker
Keyword(s):  
Experimental Study ◽  
Silicon Nitride ◽  
Room Temperature ◽  
Grit Size ◽  
Diamond Grit ◽  
Room Temperature Strength

An experimental study was conducted to evaluate the effect of several grinding variables on the room temperature strength of Norton NC-132 hot pressed silicon nitride. The grinding variables studied included diamond grit size, diamond concentration, type of diamond bond, downfeed rate and type of cut. Significant effects on strength were noted for all variables except diamond concentration.

scholarly journals Hot Pressed Silcon Nitride for Gas Turbine Applications

1972 ◽  
Author(s):  
M. L. Torti ◽  
G. Q. Weaver ◽  
D. W. Richerson
Keyword(s):  
Elevated Temperature ◽  
Silicon Nitride ◽  
Thermal Shock ◽  
Gas Turbine ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
Promising Candidate ◽  
Shock Resistance ◽  
Room Temperature Strength

The high strengths now attainable with hot pressed silicon nitride combined with its good oxidation and thermal shock resistance make it a most promising candidate for advanced gas turbine hot components. This form of silicon nitride has flexural strengths of 110,000 psi at room temperature and 60,000 psi at 1200 C. A recent experimental version of the system has exhibited room temperature strength of 145,000 psi and elevated temperature (1200 C) strength of 100,000 psi. This may be the highest strength reported on any material at this elevated temperature.

scholarly journals Treatment of Mining and Thermoelectric Waste Through the Geopolymerization Process

2021 ◽  
Vol 100 ◽  
pp. 05003
Author(s):  
Morales-Aranibar Carlos ◽  
Linares Nataniel ◽  
Soto Tolomeo ◽  
Morales-Aranibar Luis
Keyword(s):  
Fly Ash ◽  
Mine Tailings ◽  
Room Temperature ◽  
Hydroelectric Plant ◽  
Chemical Characterization ◽  
Second Stage ◽  
Pyrite Content ◽  
Two Stages ◽  
Sem Morphology

Currently, energy and extraction activities generate large amounts of highly polluting waste, so there is a need for sustainable and environmentally friendly technologies. The aim of the study is to treat mining tailings and fly ash through the process of geopolymerization. The samples studied were obtained from the Toquepala mine, Tacna and from the ENGIE-Moquegua hydroelectric plant (Peru). The methodology was based on two stages, the first characterization of Fly Ash (FA) and mine tailings (MT) by EDX chemical characterization, SEM morphology, the second was prepared mixtures of MT and FA in 10 M alkaline solution, cured in 35 days at room temperature and the characterization of the geopolymer by organoleptic analysis, SEM and TCLP. The first stage shows high aluminosilicate content 20.44% Al2O3 and 53.39 % SiO2 for (MT); 22.11% Al2O3 and 51.76% SiO2 for (FA), presents metal and pyrite content. In the second stage, the samples show health and environmental harmlessness, with the formation of tetragonal structures typical of the geopolymer, the samples show a significant reduction of Sr, Ca, Fe, Pb, Ba, Be, and Cu, demonstrating the effectiveness of treatment by means of geopolymerization opening a new field for the environmental passive treatment.

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