Repository of NNCT (Nagano National College of Technology)
Not a member yet
1122 research outputs found
Sort by
Manufacturing and mechanical properties of TiB2-B4C composite ceramics by spark plasma sintering
Get PDFTiB2-B4C ceramic composites containing 0 up to 100 mol%B4C (20mol%steps) were fabricated from a mixture of TiB2 and B4C powders by Spark Plasma Sintering(SPS) method. The derived TiB2-B4C composite containing 40～60 mol%B4C had high properties: a relative density of 95.9～97.2%, Vickers hardness of 30.2～30.4 GPa, flexural strength of 737～770 MPa, fracture toughness (KIC) of 4.99～5.99 MPa･ｍ1/2, Young's modulus of 459～480 GPa, and electrical conductivity of 0.253～1.32 MS/m. The composites present high mechanical properties compared with those for TiB2 or B4C single phase. Thus, the composites are suitable as ceramic mold materials machinable by electric discharge.departmental bulletin pape
Exploring the "Guocheng" of Lin'an Understanding its Place in the History of Imperial Capitals
Get PDFConsidering the absence of outer walls to defend the urban center of Lin'an: A comparative historical analysis. Firstly, the exiled Southern Song dynasty intentionally did not develop Lin'an as a complete capital city, despite it being the imperial court. One point of discussion is the lack of an outer defensive wall even as the population of the city grew. This can be linked to the conflict between the New and Old Law factions during the Northern Song dynasty, and their relationship with city walls and suburban shrines. The early Southern Song government took the position of the Old Law faction, as demonstrated by their support of Empress Yuan You, and may have been unable to rebuild the grand Kaifeng outer city, which was a symbol of the New Law faction. Moreover, in the context of ceremonial rites, the Nanjiao ceremonies in Lin'an were held during the reigns of Gaozong, which were not the Tian Di Fen Ji (Separate Worship of Heaven and Earth) but the earlier Tian Di He Ji (Joint Worship of Heaven and Earth), and the construction of the Earth Altar (Fang Qiu) did not take place. These points were explored in-depth by comparing them to the construction of the central capital(Zhongdu) by the Hailing King, who aimed to unify China.departmental bulletin pape
Mechanical and electrical properties of pure TiN ceramics by pressureless sintering －Effects of the sintering temperature and time－
Get PDFThe mechanical and electrical properties of pure TiN ceramics produced by the pressureless sintering method in an Ar atmosphere were investigated. In the experiment, the powder was molded at 98 MPa, and then sintering was performed at 1800-2250°C (150°C steps) with a constant sintering time of 60 minutes, and 30, 60, 120 and 180 minutes with a constant sintering temperature of 2100°C.
The properties of the sample sintered at 2100°C for 60 minutes are as follows. The relative density is 70.5%, Vickers hardness is 7.66 GPa, 4-point bending strength is 143MPa, fracture toughness (KIC) is 2.91 MPa･m1/2, Young's modulus is 356 GPa, Charpy impact strength is 19.1 kJ/m2, linear shrinkage is 7.56%, longitudinal wave speed of sound is 8.83km/s, transverse wave speed of sound is 5.33km/s, electrical conductivity is 1.51MS/m. TiN is a material that is difficult to sinter, but the pressureless sintering method is not subject to shape restrictions, so it is highly useful industrially.departmental bulletin pape
YAG-laser machining of TiO2 ceramics and its mechanical property
Get PDFSingle-shot processing and cutting processing were performed on both CIP and HIP-treated TiO2 ceramics using YAG laser, and the basic mechanical properties by the processing were investigated. Increasing the pulse height and pulse width of the machining shot pulse increases the laser beam power and energy, and basically increases the diameter and depth of the beam hole. This relationship holds true for CIP-treated TiO2, but it is not always true for HIP-treated high-density products, which sometimes cracked. In cutting processing, the hardness of the machined surface was maintained at about 80% of that of the non-machined surface. The surface roughness of the machined surface was greatly deteriorated.departmental bulletin pape
Mechanical and electrical properties of hot-pressed 3YZ-TiB2 composite ceramics
Get PDFUsing 3YZ(ZrO2/3mol%Y2O3) and pure TiB2 powders, 3YZ-TiB2 composite ceramic system (composition change in 20mol% steps) was hot-pressed in an Ar atmosphere at a temperature of 1500-1950℃ for 1 hour with a mold pressure of 28.3 MPa. The mechanical and electrical properties revealed the following. The fabricated 3YZ-TiB2 composites were highly densified with a relative density of 96.3% or more. In particular, the (3YZ)0.2(TiB2)0.8 composite exhibited a bulk density of 4881kg/m3 with a relative density of 99.7%. The sample has a Vickers hardness of 23.7GPa, Young's modulus of 501GPa, rigidity of 220GPa, three-point bending strength of 396MPa, fracture toughness (KIC) of 6.22MPa･m1/2 and surface roughness Ra of 67.3 nm. The electrical conductivity was 2.72MS/m, which is comparable to that of metals.departmental bulletin pape
Writing Fluency and Student Attitudes Towards Writing Promoted Through Weekly Online Journal Writing
Get PDFdepartmental bulletin pape
Fabrication and characterization of ceramics/Carbere composite by spark plasma sintering method
Get PDFIn this research, CSCNT (cup-stacked type carbon nano tube, Carbere) was mixed with three kinds of ceramic matrix such as SiC, WC, TiB2 by 3vol%. The ceramics/Carbere composites were sintered by spark plasma sintering method to improve mechanical and electrical properties such as the toughness, the flexural strength, the electric conductivity. Carbere existed at the grain boundaries of ceramics. The flexural strength was enhanced by 1.35 times in the WC system. The fracture toughness (KIC value) was improved about 1.1 times for the three systems. The electrical conductivity was improved about 390 times in the SiC system.departmental bulletin pape
Philosophical Analysis of Newton's "Rule V of Reasoning"―The Status of "Sense" in Experimental Philosophy―
Get PDFIn his unpublished manuscripts, Isaac Newton prepared "Rule V of Reasoning" in addition to four rules in the third edition of the Principia. This manuscript indicates that not only external, but also internal phenomena (ex. "I think" [cogito], or "I am" [sum]) could be the object of his experimental philosophy. Although this is abandoned project in the published edition, it is worth to focus on this rule because we can consider it as the projection of Newton's main task of the clarification of the nature of his experimental philosophy. In this rule, he tried to establish his philosophical and scientific position through the contesting against Cartesian "cogito ergo sum".departmental bulletin pape
Development of prototypes of new handheld snow remover
Get PDFNew handheld snow removing equipment were researched in this study. Concept for the equipment that "Easy to use for many people, and reduce physical burden on the snow removing work" was established．Tow types of prototype; snow shovel with heating system and snow pusher with variable plow system were developed and evaluated. Both prototypes indicated potential of the concept with some problem to be solved. Throughout all of investigation in this study, what is an "ideal" handheld snow remover for today, were discussed.departmental bulletin pape