Carbides deposition

Free-energy-concentration diagrams have been used in the study of the thermodynamic influence on the non-stoichiometry of the solid titanium carbide deposited from H2-CH4-TiCl4 gas mixtures at 1 900 K. The authors show how, from the partial pressure measurements of Ti vapour over a range of... 

The fracture toughness values of the silicon carbide deposits on steel thus calculated (cf. Table 6) are of the same order of magnitude as the toughness of a sintered silicon carbide (1 to 4 MPa.m On a tantalum substrate, these are lower. These differences are probably due to residual stresses which vary considerably depending on the nature of the underlying substrate. 

Here, carbon contamination is reduced because most of the carbon in the precursor molecule is used to construct the carbide deposit. Only incomplete pyrolysis products contaminate the film. 

Besmann TM, Sheldon BW, Moss TS, Kaster MD (1992) Depletion effects of silicon carbide deposition from methyltrichlorosilane. J Am Ceram Soc 75 2899-... 

Lespoaux D, Langlais F, Naslain R (1995) Correlations between gas phase supersaturation, nucleation process and physico-chemical characteristics of silicon carbide deposited from Si-C-H-Cl system on silica substrate. J Mater Sci 30 1500-1510... 

Boron fibers are used to reinforce different epoxy or light-metal matrices. To hinder interactions with metals, they should be protected by boron carbide deposits obtained by chemical vapor deposition. Boron carbide fibers can be prepared directly by reaction of boron obtained by the reduction of BCI3 on carbon fibers. ... 

KEYWORDS effect temperature field CVD boron carbide deposition mechanism 1. INTRODUCTION... 

In this work, the effect of two kinds of temperature field on boron carbide deposition was investigated. Firstly, two kinds of temperature field were compared, which were named field A and field B respectively. Then, morphologies, phase, composition and structure of boron carbide under field A and field B were characterized and compared. Finally, different deposition mechanisms were proposed to explain the difference of deposits under field A and field B. 

Figure.2 SEM photos of surface morphologies for boron carbide deposited at different temperature...

To know B-C bond state, the FTIR was used to characterize the deposits. The FTIR spectrums of boron carbide deposited at different temperature fields were shown in Fig.6. The main absorb peaks of deposits under two kinds temperature fields were 1082.26 cm , 792.13 cm" and 485.36... 

M, Karaman, H. Ozbelge, N. Sezgi, and T. Dogu, Mechanism and characterization studies on boron carbides deposited by chemical vapor deposition technique. Mater. Res. Soc. Symp. Proc., 886, 455-460(2006)... 

It is thought to start with chromium carbide deposits along grain boundaries that leave the metal open to corrosion. This form of corrosion is controlled by maintaining low chloride ion and oxygen content in the environment and use of low carbon steels. 

Figure 9. Hardness of amorphous boron carbide deposited from diborane and methane by plasma CVD against the composition (upper scale) and the C B ratio in the gas inlet.

Many badly worn parts are first built up to almost finished sl2e with a high-carbon electrode, then surfaced with an austenitic rod, and finally a few beads of chromium carbide deposit are placed in spots requiring maximum protection against abrasion. Regardless of the circumstances, a careful analysis of the surfacing problem will be well worthwhile. Examples of jobs are shown in Figures 24.33 to 24.35. 

The sandwich technique has the advantage that it enables the analytical sample to react in a bath which is probably not yet saturated with carbon, and from which the escape of carbon monoxide is thus not yet impeded by needles of graphite or carbide deposited on the surface of the bath, as frequently occurs in the bath procedure. In addition, a further considerable effect on the release of gas, is obtained by the fact that titanium and zirconium form alloys with platinum or palladium, which results in a large evolution of heat. This causes a sudden and considerable increase in temperature (a flash of light ). The sandwich method is however limited to bath metals with very low oxygen contents, which is e.g. not the case with nickel, cobalt or iron. Therefore, the metal foil required is preferably a piece of platinum or palladium foil of about 50 Mm thick. The oxygen blank values of platinum and palladium in compact form are between 1 and 5 Mg/g. They amount to 5 to 15 Mg/g for the corresponding foils. 

---