scholarly journals Nitrogen Availability Of Nitriding Atmosphere In Controlled Gas Nitriding Processes

2015 ◽  
Vol 60 (2) ◽  
pp. 747-754 ◽  
Author(s):  
J. Michalski ◽  
K. Burdyński ◽  
P. Wach ◽  
Z. Łataś
Keyword(s):  
Flow Rate ◽  
Nitrogen Availability ◽  
Dissociation Rate ◽  
Process Temperature ◽  
Nitriding Process ◽  
Variable Parameters ◽  
Gas Nitriding ◽  
Nitriding Potential

Abstract Parameters which characterize the nitriding atmosphere in the gas nitriding process of steel are: the nitriding potential KN, ammonia dissociation rate α and nitrogen availabilitymN2. The article discusses the possibilities of utilization of the nitriding atmosphere’s nitrogen availability in the design of gas nitriding processes of alloyed steels in atmospheres derived from raw ammonia, raw ammonia diluted with pre-dissociated ammonia, with nitrogen, as well as with both nitrogen and pre-dissociated ammonia. The nitriding processes were accomplished in four series. The parameters selected in the particular processes were: process temperature (T), time (t), value of nitriding potential (KN), corresponding to known dissociation rate of the ammonia which dissociates during the nitriding process (α). Variable parameters were: nitrogen availability (mN2), composition of the ingoing atmosphere and flow rate of the ingoing atmosphere (FIn).

White Layer Control in Gas Nitriding Process Using an Oxygen Sensor

2012 ◽  
Vol 579 ◽  
pp. 278-286 ◽  
Author(s):  
Han Ming Chen ◽  
Yu Chi Lin ◽  
Yong Chwang Chen
Keyword(s):  
Flow Rate ◽  
Output Voltage ◽  
Oxygen Sensor ◽  
White Layer ◽  
Experimental Results ◽  
Nitriding Process ◽  
Hardness Distribution ◽  
Gas Nitriding ◽  
Layer Control

There are many advantages in nitriding process, but the formation of white layer sometimes results in trouble. The formation of white layer can be reduced by controlling the nitriding atmosphere appropriately. In this experiment, the nitriding atmosphere is prepared by mixing NH3 and H2. An oxygen sensor is used to detect the condition of the atmosphere, and the value of output voltage (EMF) is used as a signal for controlling the flow rate of H2. The experimental results show that the thickness of white layer can be reduced effectively by controlling the flow rate of H2 through the voltage reading of the atmosphere. Meanwhile, the hardness and the depth of nitriding layer could still be maintained. For nitriding at 550 °C, no white layer is formed when EMF is controlled above 1160 mV and a satisfying hardness distribution of the nitriding layer can be obtained when EMF is controlled at 1140 mV.

Optimizing Conditions for Formation of Local Zones for Thermomigration in Silicon

2017 ◽  
Vol 265 ◽  
pp. 839-844
Author(s):  
B.M. Seredin ◽  
V.P. Popov ◽  
A.N. Zaichenko
Keyword(s):  
Flow Rate ◽  
Protective Coating ◽  
Silicon Oxide ◽  
Defect Formation ◽  
Relative Number ◽  
Silicon Wafers ◽  
Process Temperature ◽  
Optimum Conditions ◽  
Surface Microrelief

The types of defects occurring during the formation of local zones on the surface of silicon wafers have been established. The dependences of defect formation on the surface from the surface microrelief, thickness of the protective coating of silicon oxide, process temperature, flow rate of the melt, the height of the melt, and the concentration of gallium additives in the aluminum have been determined. The optimum conditions of the process of zones formation have been revealed, and the total relative number of all types of defects has been significantly reduced.

scholarly journals The influence of laser re-melting on microstructure and hardness of gas-nitrided steel

2016 ◽  
Vol 36 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Dominika Panfil ◽  
Piotr Wach ◽  
Michał Kulka ◽  
Jerzy Michalski
Keyword(s):  
Laser Beam ◽  
Laser Treatment ◽  
Diffusion Zone ◽  
Nitrided Layer ◽  
Nitriding Process ◽  
Beam Power ◽  
Gas Nitriding ◽  
Nitrided Steel ◽  
Laser Beam Power ◽  
And Diffusion

Abstract In this paper, modification of nitrided layer by laser re-melting was presented. The nitriding process has many advantageous properties. Controlled gas nitriding was carried out on 42CrMo4 steel. As a consequence of this process, ε+γ’ compound zone and diffusion zone were produced at the surface. Next, the nitrided layer was laser remelted using TRUMPF TLF 2600 Turbo CO2 laser. Laser tracks were arranged as single tracks with the use of various laser beam powers (P), ranging from 0.39 to 1.04 kW. The effects of laser beam power on the microstructure, dimensions of laser tracks and hardness profiles were analyzed. Laser treatment caused the decomposition of continuous compound zone at the surface and an increase in hardness of previously nitrided layer because of the appearance of martensite in re-melted and heat-affected zones

HAYNES NS-163 Alloy: A Novel Nitride Dispersion-Strengthened CO-Base Alloy

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Michael G. Fahrmann ◽  
Vinay P. Deodeshmukh ◽  
S. Krishna Srivastava
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Oxidation Resistance ◽  
Base Alloy ◽  
Nitriding Process ◽  
Dispersion Strengthening ◽  
Annealed Condition ◽  
Gas Nitriding ◽  
Diffusion Controlled ◽  
Structural Applications

HAYNES® NS-163® alloy was developed by Haynes International Inc., Kokomo, IN, for high-temperature structural applications by pursuing a dual manufacturing approach: the fabrication of components in the readily weldable and formable mill-annealed condition, and their subsequent strengthening by means of a gas nitriding process. The latter process results in dispersion-strengthening by virtue of formation of internal nitrides. Since this process is diffusion-controlled, component section thicknesses are limited to approximately 2.0 mm (0.080 in.). Microstructures and mechanical properties of nitrided sheet samples are presented. Oxidation resistance and the need for coatings at temperatures exceeding 980 °C (1800 °F) are addressed as well.

Optimization of Jc for Photo-Assisted MOCVD Prepared YBCO Thin Films by Robust Design

1993 ◽  
Vol 335 ◽  
Author(s):  
P. C. Chou ◽  
Q. Zhong ◽  
Q. L. Li ◽  
A. Ignatiev ◽  
C. Y. Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Robust Design ◽  
Flow Rate ◽  
Chemical Vapor ◽  
Preparation Technique ◽  
Superconducting Thin Film ◽  
Variable Parameters ◽  
Ybco Thin Films ◽  
Thin Film Preparation ◽  
Phase Design

AbstractMetalorganic chemical vapor deposition (MOCVD) is emerging as a practical high Tc superconducting thin film preparation technique for industrial application. Intrinsically this technique involves a large number of variable parameters. This is especially critical for the quarternary or higher high Tc materials. Thus, effective methods are required to optimize the parameters for the preparation of high Tc films. A matrix experimental design named Robust Design has been employed for this purpose. The first-phase design was based on a starting knowledge of growth temperature and pressure, and annealing temperature for MOCVD preparation of YBCO thin films. A minimum lab effort of only nine deposition experiments was then used to optimize the process control parameters of precursor oven temperature, carrier gas (Ar) flow rate, O2 flow rate and N2O flow rate. The results were then followed by three confirmation depositions. The Robust Design resulted in the growth of YBCO film with Tc consistently in the range of 87.0 K to 90.2 K and Jc improved from about 1.0 × 106 A/cm2 to 3–5 × 106 A/cm2.

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