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Box: 87 Helwan, Cairo, Egypt 2 Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047, Japan Keywords: Si2N2O, SHS, desert sand, nitriding combustion, β-Si3N4 Abstract.
The use of the self-propagating high temperature synthesis, SHS, or combustion method in synthesizing advanced ceramics has proved to be successful since the process was discovered by Russian scientists in late 1967 [8].
In this work, we applied the SHS method to prepare silicon oxynitride by selecting cheap starting materials, desert sand and reclaimed silicon which is a byproduct of zinc smelting industry.
Figure 1: Schematic diagram of SHS apparatus (combustion furnace): (1) burden, (2) ignition agent, (3) porous container, (4) thermocouple, (5) carbon ribbon, (6) electrodes, (7) high-pressure chamber, (8) nitrogen gas atmosphere, and (9) glass window for observation.
Fig. 4 shows the scanning electron micrograph of the silicon oxynitride powder obtained, which consists of fine particles with particle size of �5 µm. 0 500 1000 1500 2000 0 30 60 90 120 150 180 210 Time (s) Temperature (o C) 0 200 400 600 800 1000 1200 15 20 25 30 35 40 2 θθθθ Counts ο Si2N2O ∆ β-Si3N4 Figure 4: SEM micrograph of synthesized product (after grinding).

Introduction SHS (Self-propagating High-temperature Synthesis, referred to as SHS) is one kind of new material preparation technologies which has been developing in recent years, its characteristic is to synthesize new materials using the internal chemical energy of reactants.
With the integration of the synthesis and sintering, the process of SHS will complete in several or dozens of seconds [4].
In this study, a large number of ceramic particles are successfully fabricated by the combinative methods of SHS and foundry, using the heat of molten steel as an external heat source and triggering the high-temperature chemical reaction in blanks.
Cut the casting into a size of 15 × 15 × 15mm as test blocks, which are prepared for scanning electron microscope samples after grinding and polishing.
SHS.

Recently, we have achieved the synthesis of their composite by hot shock compaction combined shock powder consolidation method and self-propagating high-temperature synthesis (SHS) [2].
The specimens for CTEM and HREM observations were prepared by a standard technique involving mechanical grinding to a thickness of 80µm, dimpling to a thickness of about 20µm at the center of the disks and additional Ar + -ion beam thinning at accelerating voltage of about 5kV.
Fig.3 HREM micrograph of interphase boundary between TiN and TiB2 in the TiN-TiB2 composite of TiN : TiB2 = 60: 40 was achieved by shock consolidation after SHS.
Summary Interfacial microstructure of TiN-TiB2 composite, which was synthesized by hot shock compaction combining shock powder consolidation and SHS, was investigated by CTEM and HREM.
J. of SHS Vol.14 (2005), p. 329

Combined SHS with casting, in-situ Al2O3 particle-reinforced copper matrix composite was fabricated.
This paper adopts SHS and traditional casting Preparation method, manufactures out the in-situ Al2O3 particles reinforced copper matrix composite, reseach Al2O3 particles reinforced phase and the influence law of loading of copper matrix composites micro frictional learning characteristic.
And under high loading, along with the friction process constantly cycling rapid reciprocating motion of the grinding ball makes its to emerge fatigue crack, until falling off, wear mechanism is typical fatigue wear (chart 5d).
Figure 5 is SEM figure of the surface topography of grinding crack amplification 2000 times under 1.0 N loading.
(3)Along with the increase of loading, the grinding crack of composite in the air changes from "W" to "U" type, abrasion mechanism also gradually shifts from adhering abrasion under low loading to fatigue abrasion.

Production of Silicon Carbide via Grinding and Heat treatment Process H.J.
This may due to the grinding mechanism of both mills.
Among these processes the most studied include mechanical milling, rapid carbothermal synthesis, SHS processes, microwave synthesis, polymer pyrolisis, sol–gel processes, CVD and laser synthesis. [3].
This is due to the difference of grinding mechanism for both planetary mill and ring mill.
The silicon carbide is obtained by grinding the waste glass and graphite powder.

These materials that are generally characterized by low adiabatic combustion temperature cannot be synthesized directly by the self-propagating high-temperature synthesis (SHS) method.
Reactant powders were weighted as stoicheometric molar ratio of Fe2O3: Al, 1:2 and then mixed in a grinding machine for 0.5 hr.
Thermodynamic calculation for equilibrium concentration of stable species produced by SHS reactions were performed based on the Gibbs energy minimization method [5].
The total Gibbs energy of the system can be express by the following equation: G = åni(g i° + RTlnPi) + ånig i° + åni(g i° + RTlnxi + RTlngi) (1) gas condensed solution In this study, Fe2O3 and Al were used as precursors for the SHS reaction.
Calculation has shown the adiabatic temperature of these reactions system that higher than 1800°C, thus the using of SHS is feasible for these systems.

CCSO is a modified form of SHS that maintains the advantages of SHS and circumvents some of its disadvantages.
In some cases, complete conversion cannot be achieved and requires grinding of the product and repeated calcination.
However, several reasons limit the utilization of SHS for certain applications, especially for the synthesis of complex oxide ceramics when SHS of oxides uses a pure metal as a combustion fuel.
SHS, 12, 3, 187-195, (2003). 13.
SHS, 16, p.36-45, (2007). 20.

SHS titanium carbide in this mixture heats it, which leads to the synthesis of tungsten carbide.
After SHS, a lot of unreacted tungsten remains in the mixture, there are phases WC, W2C.
The diffraction pattern of the products of SHS (50% WC and 50% TiC, simple stirring, the excess carbon black – 2 times) Table 2 shows data on the phase composition of all samples after SHS.
Size of SHS products OCD № Composition in terms of carbides, % Excess soot Time MA to SVS, min.
In all modified samples (figures 7, 8) there is a grinding of graphite inclusions in comparison with the control sample 1 (figure 6).

The cold-pressed specimen was put into a special SHS reactor [9].
Bending specimens were cut from the two-time hot-pressed products followed by surface grinding and polishing (sample size = 5 mm × 5 mm × 35 mm and span = 30 mm).
Results and Discussion Microcosmic defects in TiB2-40wt%Cu cermet produced by SHS.
(a) SHS; (b) 1050°C; (c) 1090°C; (d) 1150°C.
Conclusions The TiB2-40wt%Cu composite was produced by SHS/PHIP.

Thus the SHS reactive mechanism transforms form solid-solid reaction into solid-liquid-solid reaction, which can increase diffusion velocity of the reactive component and accelerate the SHS reaction.
In this study, using Ti-B4C-sucrose (precursor of carbon) -5wt.% Al as the SHS reactive system, Ti(C,N)-TiB2 composite ceramic performs were prepared by self-reactive spray formed technology.
Using modified spray formed equipments to spray test and graphite grinding tool as acceptors.
In this study, temperature of ceramic droplet after the SHS reaction can nearly reach at 3000ºC [12], which can meet the requirement of TiB2 grain growth orientation and make there are complete TiB2 rodlike crystals in the products.
Zhu [14] has studied on toughening mechanism of TiC-TiB2/Cu composite materials prepared by SHS/PHIP.