scholarly journals Dense, Strong, and Precise Silicon Nitride-Based Ceramic Parts by Lithography-Based Ceramic Manufacturing

2020 ◽  
Vol 10 (3) ◽  
pp. 996 ◽  
Author(s):  
Altan Alpay Altun ◽  
Thomas Prochaska ◽  
Thomas Konegger ◽  
Martin Schwentenwein
Keyword(s):  
Surface Roughness ◽  
High Temperature ◽  
Light Scattering ◽  
Silicon Nitride ◽  
Material Properties ◽  
Refractive Indices ◽  
High Relative Density ◽  
Ceramic Manufacturing ◽  
High Level ◽  
First Time

Due to the high level of light absorption and light scattering of dark colored powders connected with the high refractive indices of ceramic particles, the majority of ceramics studied via stereolithography (SLA) have been light in color, including ceramics such as alumina, zirconia and tricalcium phosphate. This article focuses on a lithography-based ceramic manufacturing (LCM) method for β-SiAlON ceramics that are derived from silicon nitride and have excellent material properties for high temperature applications. This study demonstrates the general feasibility of manufacturing of silicon nitride-based ceramic parts by LCM for the first time and combines the advantages of SLA, such as the achievable complexity and low surface roughness (Ra = 0.50 µm), with the typical properties of conventionally manufactured silicon nitride-based ceramics, such as high relative density (99.8%), biaxial strength (σf = 764 MPa), and hardness (HV10 = 1500).

Phthalonitrile-carbon fiber composites produced by vacuum infusion process

2017 ◽  
Vol 51 (30) ◽  
pp. 4157-4164 ◽  
Author(s):  
BA Bulgakov ◽  
AV Sulimov ◽  
AV Babkin ◽  
IA Timoshkin ◽  
AV Solopchenko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Carbon Fiber ◽  
Carbon Fiber Composites ◽  
Vacuum Infusion ◽  
Reinforced Plastics ◽  
Composite Tooling ◽  
High Level ◽  
First Time ◽  
Vacuum Infusion Process

High-temperature carbon fiber-reinforced plastics based on phthalonitrile resins are obtained for the first time by vacuum infusion process. For this purpose, formulations based on low-melting bis(3-(3,4-dicyanophenoxy)phenyl) phenyl phosphate monomer in combination with 1,3-bis(3,4-dicyanophenoxy)benzene and 4-[3-(prop-2-yn-1-yloxy)phenoxy]benzene-1,2-dicarbonitrile were developed. Resin viscosities η ≤ 600 mPa·s were suitable for VIP and at the same time the thermal and mechanical properties of the cured matrices were in high level featured to phthalonitriles (HDT ≥ 420℃, E ≥ 5.1 GPa). CFRP samples were manufactured by vacuum infusion process with carbon fabric and demonstrated thermal stability over 400℃ and a change of mechanical properties by less than 10% at 300℃. Present results sufficiently extend the application field of phthalonitriles as matrices for complex-shape high temperature composite parts in aerospace or high-temperature composite tooling for PEEK-like thermoplastics processing.

Surface Roughness Characteristics of Finely Ground Ceramics

2006 ◽  
Vol 532-533 ◽  
pp. 416-419 ◽  
Author(s):  
Jian Yun Shen ◽  
Wei Min Lin ◽  
Hitoshi Ohmori ◽  
Xi Peng Xu
Keyword(s):  
Surface Roughness ◽  
Silicon Nitride ◽  
Material Properties ◽  
Brittle Materials ◽  
Mesh Size ◽  
Silicon Nitride Ceramic ◽  
Engineering Ceramics

In the present study, surface roughness after grinding with different mesh size diamond wheels were measured to study the surface roughness characteristics of engineering ceramics. According to the surface behaviours and measured surface roughness, the relation between the surface roughness and the properties of these brittle materials was described. Coupled with the micro-observation of ground surfaces, it was concluded that the grinding condition and material properties led to the differences of surface roughness characteristics of brittle materials. The silicon nitride ceramic was the most easily machined to ductile surface among these ceramics.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

Electron Microscopy of Silicon Nitride-Based Ceramics

1991 ◽  
Vol 49 ◽  
pp. 926-927
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Silicon Nitride ◽  
World Wide ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
High Temperature Strength ◽  
Sintering Additives ◽  
Glass Forming ◽  
Dense Product

Silicon nitride and silicon nitride based-ceramics are now well known for their potential as hightemperature structural materials, e.g. in engines. However, as is the case for many ceramics, in order to produce a dense product, sintering additives are utilized which allow liquid-phase sintering to occur; but upon cooling from the sintering temperature residual intergranular phases are formed which can be deleterious to high-temperature strength and oxidation resistance, especially if these phases are nonviscous glasses. Many oxide sintering additives have been utilized in processing attempts world-wide to produce dense creep resistant components using Si3N4 but the problem of controlling intergranular phases requires an understanding of the glass forming and subsequent glass-crystalline transformations that can occur at the grain boundaries.

A Confrontation between Two Doctrines: The Birth of Struggle for Hegemony in Hebrew Children's Literature during the 1930s and 1940s

2008 ◽  
Vol 1 (2) ◽  
pp. 139-155 ◽  
Author(s):  
YAEL DARR
Keyword(s):  
Children's Literature ◽  
Educational System ◽  
Single Channel ◽  
Children’S Literature ◽  
The Political ◽  
Literary Creation ◽  
History Of ◽  
High Level ◽  
First Time ◽  
Literary Quality

This article describes a crucial and fundamental stage in the transformation of Hebrew children's literature, during the late 1930s and 1940s, from a single channel of expression to a multi-layered polyphony of models and voices. It claims that for the first time in the history of Hebrew children's literature there took place a doctrinal confrontation between two groups of taste-makers. The article outlines the pedagogical and ideological designs of traditionalist Zionist educators, and suggests how these were challenged by a group of prominent writers of adult poetry, members of the Modernist movement. These writers, it is argued, advocated autonomous literary creation, and insisted on a high level of literary quality. Their intervention not only dramatically changed the repertoire of Hebrew children's literature, but also the rules of literary discourse. The article suggests that, through the Modernists’ polemical efforts, Hebrew children's literature was able to free itself from its position as an apparatus controlled by the political-educational system and to become a dynamic and multi-layered field.

Experimental investigation and modelling of light scattering in a-Si:H solar cells deposited on glass/ZnO:Al substrates

2002 ◽  
Vol 715 ◽  
Author(s):  
J. Krc ◽  
M. Zeman ◽  
O. Kluth ◽  
F. Smole ◽  
M. Topic
Keyword(s):  
Surface Roughness ◽  
Experimental Investigation ◽  
Solar Cells ◽  
Angular Distribution ◽  
Light Scattering ◽  
Optical Model ◽  
Distribution Functions ◽  
Interface Roughness ◽  
Scattering Parameters ◽  
Good Agreement

AbstractThe descriptive scattering parameters, haze and angular distribution functions of textured ZnO:Al transparent conductive oxides with different surface roughness are measured. An approach to determine the scattering parameters of all internal interfaces in p-i-n a-Si:H solar cells deposited on the glass/ZnO:Al substrates is presented. Using the determined scattering parameters as the input parameters of the optical model, a good agreement between the measured and simulated quantum efficiencies of the p-i-n a-Si:H solar cells with different interface roughness is achieved.

NIROSTA 4002

Alloy Digest ◽  
2002 ◽  
Vol 51 (6) ◽  
Keyword(s):  
Hydrogen Sulfide ◽  
High Temperature ◽  
Physical Properties ◽  
Structural Steel ◽  
Oil Industry ◽  
Heat Treating ◽  
Mineral Oil ◽  
Chromium Steel ◽  
Temperature Performance ◽  
High Level

Abstract NIROSTA 4002 is an apparatus structural steel with 13% Cr. It is used for crack-resistant installations in the mineral oil industry because it has a high level of resistance against hydrogen and hydrogen sulfide. This chromium steel requires a smoothened surface free from residues in order to achieve optimal resistance to corrosion. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SS-856. Producer or source: ThyssenKrupp Nirosta GmbH.

AL 4565 ALLOY

Alloy Digest ◽  
2004 ◽  
Vol 53 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
High Resistance ◽  
Flue Gas ◽  
Heat Treating ◽  
Flue Gas Desulfurization ◽  
High Nitrogen ◽  
Temperature Performance ◽  
High Level

Abstract AL 4565 alloy has a high level of austenitizers, which provides the microstructure with a high resistance to sigma formation during welding. The high nitrogen also gives the alloy superior strength among the austenitics. Applications include flue gas desulfurization and handling seawater. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as heat treating and joining. Filing Code: SS-906. Producer or source: Allegheny Ludlum Corporation.

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