Modeling and Experiment on Physical and Chemical Liquid Deposition Processes for Rapid Tooling and Manufacturing

2000 ◽  
Author(s):  
Zongyan He ◽  
Jack G. Zhou
Keyword(s):  
Heat Transfer ◽  
Theoretical Models ◽  
Nucleation And Growth ◽  
Free Form ◽  
Technical Problems ◽  
Chemical Liquid Deposition ◽  
Deposition Processes ◽  
Physical And Chemical ◽  
Solid Free Form Fabrication ◽  
Liquid Deposition

Abstract A new solid free-form fabrication (SFF) technique, named Physical and Chemical Liquid Deposition (P/CLD), is introduced in this paper, and then several key technical problems are stated. In order to solve these problems, theoretical models to describe the nucleation and growth of deposits in PLD, the chemical dynamic process in CLD, and the heat transfer in P/LCD are studied. To determine the heat transfer parameters, some experiments are designed and experimental results are presented.

Thermal Analysis of a New Metal-Deposition Rapid Prototyping Process

1996 ◽  
Author(s):  
Ronald K. Worth ◽  
Philip Barkan
Keyword(s):  
Heat Transfer ◽  
Finite Difference ◽  
Rapid Prototyping ◽  
Metal Deposition ◽  
Free Form ◽  
Transfer Model ◽  
Key Innovation ◽  
Critical Problems ◽  
Key Aspects ◽  
Solid Free Form Fabrication

Abstract Rapid prototyping with solid free-form fabrication (SFF) is a key innovation that makes it possible to rapidly produce physical parts directly from a CAD model. Recent research focuses on SFF systems which directly fabricate metal parts. This paper introduces the Stanford Solid Plotter (SSP), a new SFF system that forms prototypes using metal-deposition. Since many critical problems in metal deposition relate to heat transfer issues, the main focus of the paper is on key aspects of the thermal behavior of the SSP part fabrication process, namely the deposition, freezing and cooling of a workpiece. Predictions from a finite difference heat transfer model are used to improve both the precision and strength of actual workpieces made with the SSP. Lab experiments using thermocouples confirm the behavior of the finite difference model.

Formation of Cf/C Composites with SiC Concentration Gradient on the Surface by SHCLD Technique

2007 ◽  
Vol 353-358 ◽  
pp. 1310-1313
Author(s):  
Guang Li Chen ◽  
Hao Ran Geng ◽  
Jun Hua Chen ◽  
Hui Li ◽  
Zhong Quan Guo
Keyword(s):  
Concentration Gradient ◽  
Deposition Process ◽  
Conventional Technique ◽  
Mechanical Tests ◽  
Gradient Layer ◽  
System Pressure ◽  
Chemical Liquid Deposition ◽  
Deposition Processes ◽  
Liquid Deposition ◽  
Different Thickness

Adopting two-step deposition processes, SiC concentration gradient layer on the surface of Cf/C composites were prepared via Self-heating Chemical Liquid Deposition (SHRCLD) technique. In second deposition process, carbon and SiC were codepositted from pure kerosene and TEOS. The temperature of deposition was 1000°C~1200°C and the system pressure was 0.1MPa. Different thickness of gradient layers would be attained via adjusting the proportion of TEOS in procurer and controlling deposition time. Oxidation resistance, and mechanical tests were investigated, and the microstructure was observed under SEM. Results showed that the flexural strength of the composites was 123.7 MPa. The antioxidation temperature of Cf/C composites with the gradient layer is up to 800°C in air. The process of SHCLD technique is simple and easy to be controlled, and the deposition rate is faster than other conventional technique.

scholarly journals Synthesis and characterization of Fe, Co, and Ni colloids in 2-mercaptoethanol

2020 ◽  
Vol 10 ◽  
pp. 184798042096688
Author(s):  
Galo Cárdenas-Triviño ◽  
Sergio Triviño-Matus
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Colloidal Dispersions ◽  
Synthesis And Characterization ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Chemical Liquid Deposition ◽  
Liquid Deposition

Metal colloids in 2-mercaptoethanol using nanoparticles (NPs) of iron (Fe), cobalt (Co), and nickel (Ni) were prepared by chemical liquid deposition method. Transmission electron microscopy, electron diffraction, UV-VIS spectroscopy, and scanning electron microscopy with electron dispersive X-ray spectroscopy characterized the resulting colloidal dispersions. The NPs exhibited sizes with ranges from 9.8 nm for Fe, 3.7 nm for Co, and 7.2 nm for Ni. The electron diffraction shows the presence of the metals in its elemental state Fe (0), Co (0), and Ni (0) and also some compounds FeO (OH), CoCo2S4, and NiNi2S4.

Menadione nicotinamide bisulphite as a source of vitamin K and niacin activities for the growing pig

2000 ◽  
Vol 71 (1) ◽  
pp. 111-117 ◽  
Author(s):  
M. Marchetti ◽  
M. Tassinari ◽  
S. Marchetti
Keyword(s):  
Vitamin K ◽  
Control Diet ◽  
Live Weight ◽  
Organic Salt ◽  
Free Form ◽  
Food Supplementation ◽  
Sodium Bisulphite ◽  
Chemical Factors ◽  
And Control ◽  
Physical And Chemical

AbstractWhen compared with other menadione derivatives such as menadione sodium bisulphite (MSB), menadione nicotinamide bisulphite (MNB), an organic salt combining menadione and nicotinamide, shows better stability towards physical and chemical factors once it is added to pre-mixes or foods. The present work evaluates the bioavailability of the two vitamins present in this compound and toxicity in the pig. To assess vitamin bioavailability, pigs were given small amounts of food containing MNB or equivalent amounts of MSB and nicotinamide in the free form. Menadione and nicotinamide concentrations in blood samples drawn at set times after the diets were given did not reveal any significant differences between the two modes of administration. Haematic levels of both vitamins in animals receiving MNB, or MSB and nicotinamide, were after 2, 4, 8 and 12 h higher (P < 0·001) than those of untreated animals. The tolerance level to MNB was evaluated in pigs given diets containing graded amounts of MNB (100, 500, 2500 mg/kg) for 28 days. No significant (P > 0·05) differences were recorded in live weight, food intake and gain/food ratio in pigs given these diets when compared with those given an unsupplemented diet. Haemoglobin and bilirubin levels did not differ between animals given various amounts of MNB and control animals. Plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in pigs given 100 mg/kg of MNB did not show significant differences when compared with those observed in pigs given an unsupplemented control diet. In pigs on the diets supplemented with 500 and 2500 mg/kg of MNB there was a significant increase in the two enzymatic activities as compared with controls (P < 0·001 and P < 0·01). In the case of ALT this had disappeared by 28 weeks. MNB is a good source of vitamin K for the pig and does not appear to have any adverse effects, even when administered at levels higher than those normally used in pig food supplementation.

Solid free-form fabrication of drug delivery devices

1996 ◽  
Vol 40 (1-2) ◽  
pp. 77-87 ◽  
Author(s):  
Benjamin M. Wu ◽  
Scott W. Borland ◽  
Russell A. Giordano ◽  
Linda G. Cima ◽  
Emanuel M. Sachs ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Free Form ◽  
Solid Free Form Fabrication ◽  
Drug Delivery Devices

scholarly journals Resilient, fire-retardant and mechanically strong polyimide-polyvinylpolymethylsiloxane composite aerogel prepared via stepwise chemical liquid deposition

2019 ◽  
Vol 183 ◽  
pp. 108096 ◽  
Author(s):  
Ze Zhang ◽  
Xiaodong Wang ◽  
Guoqing Zu ◽  
Kazuyoshi Kanamori ◽  
Kazuki Nakanishi ◽  
...  
Keyword(s):  
Fire Retardant ◽  
Composite Aerogel ◽  
Chemical Liquid Deposition ◽  
Liquid Deposition

A Model of Silicon Nanocrystal Nucleation and Growth on SiO2 by CVD

2004 ◽  
Vol 830 ◽  
Author(s):  
M. W. Stoker ◽  
T. P. Merchant ◽  
R. Rao ◽  
R. Muralidhar ◽  
S. Straub ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Flash Memory ◽  
Silicon Nanocrystals ◽  
Large Scale ◽  
Process Development ◽  
Electron Tunneling ◽  
Nucleation And Growth ◽  
Scale Model ◽  
Size Distributions ◽  
Deposition Processes

ABSTRACTSilicon nanocrystals can be used in non-volatile memory devices to reduce susceptibility to charge loss via tunnel oxide defects, allowing scaling to smaller sizes than possible with conventional Flash memory technology. In order to optimize device performance, it is desirable to maximize the nanocrystal density and surface coverage, while maintaining sufficient inter-crystallite separation to limit electron tunneling between adjacent crystallites. Ideally, crystallite densities in excess of 1012cm-2 with relatively narrow particle size distributions must be obtained, posing a significant challenge for process development and control. In order to facilitate development of such a process, a rate-expression-based model has been developed for the nucleation and growth of silicon nanocrystals on SiO2 in a CVD process. The model addresses the phenomena of nucleation, growth, and coalescence and includes the effects of exclusion zones surrounding the growing nuclei. The model uses a phenomenological expression to describe the nucleation rate and assumes that following nucleation, crystallite growth is dominated by gas-phase deposition processes, analogous to CVD of polycrystalline silicon. The model-predicted time-evolutions of crystallite densities and crystallite size distributions are consistent with experimental distributions as measured by Scanning Electron Microscopy (SEM). By coupling the model to a reactor-scale model of polysilicon CVD, it is possible to predict variations in the crystallite size distributions at various locations across a wafer as a function of reactor settings (temperature, pressure, flow rates, etc…). This in turn can be used for process control and optimization in order to ensure uniform deposition of nanocrystals in a large-scale manufacturing environment.

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