Mired field microwave sintering cavity with orientational reflective mirror
The utility model relates to a kind of mixing field pattern microwave agglomerating furnace cavity class.
Microwave sintering has obtained various countries researcher's abundant attention and research energetically as a kind of novel fast ceramic sintering technology.The microwave sintering cavity is the core of microwave sintering equipment.The appropriate design of cavity, elaborate and correct the adjustment is the key that realizes successful agglomerated material.Present microwave sintering cavity has two kinds of single mode resonator and multimode cavities.One-mode cavity have field distribution simple, stablize, be easy to adjust and advantages such as control, but its thermal treatment zone is too little, can only be used for the microwave sintering of laboratory subsized specimen sample.There is the uneven shortcoming of heat distribution in the multimode cavity, though it under correct design and adjusting, enlarges the homogeneous heating district by improving mode spectrum density and changing distribution.But in fact multimode cavity endoceliac " hot-zone " distributes always uneven, sometimes difference is also quite big, this is because it used is general industry usefulness microwave frequency band (0.915GHZ and 2.45GHZ), the mode of operation that may exist in the chamber is always limited, can not eliminate fully because the existence of node and circling point causes the uneven distribution of field intensity.For improving it, people adopt two kinds of methods mostly at present: the one, improve operating frequency, the 28GHZ microwave source is adopted in OKa Ridge laboratory as the U.S., and enlarged cavities, the ratio that makes cavity size and microwave wavelength forms disresonance chamber (be actually the mode of resonance number and be tending towards unlimited many) and realizes the field intensity homogenising in the whole chamber greater than 100.The shortcoming of this method is that equipment manufacturing cost is high, and operating cost is big.The 2nd, adopt mode stirrer, change the cavity mode of operation periodically, improve uniformity, but this effect is limited, and can't satisfies the requirement of microwave sintering temperature homogeneity.
The purpose of this utility model is to set up a directed reflection convergence apparatus in common multimode cavity, and microwave focousing field and stationary field in the chamber are synthesized and superposition, forms bigger microwave field homogeneity range, to realize the microwave sintering to the ceramic material of large-size.
The purpose of this utility model realizes in the following manner, sets up a microwave directional mirror 3 in common multimode cavity 5, and speculum 3 is suspended in the cavity by rotation and lifting axle 2.
Accompanying drawing is the utility model structural representation.Motor, 4-ceramic material, 6-ceramic material carriage, 7-microwave energy-feeding mouth, 8-chamber door when 1-goes on foot among the figure.The utility model is set up a directed speculum 3 in microwave sintering cavity 5, it is the surperficial and multilist face focusing principle of the list like in photosensitiveness and the Microwave Optics that utilizes microwave, in multimode cavity, set up a microwave focousing field and with original stationary field superposition, with even place size in the enlarged cavity.Simultaneously speculum 3 is designed in resonant condition, not only play reflect focalization, and form source of secondary radiation, add phase compensation and orienting reflex, make focousing field in synthetic, account for quite great proportion with certain gain.Through our test shows, the quasi-static mould composition in the former multimode cavity has been weakened in this synthetic field, is subjected to the influence of external parameter (as medium electric parameter in the chamber etc.) less, and field pattern is more stable.
Speculum 3 adopts low-loss good conductor metal material (as copper, aluminium etc.) to make, and eyeglass is circular parabolic.The geometry of speculum and size can be according to cavitys, and the size of sintered body changes.The position of speculum in cavity can be regulated by spiral lifting axle 2.By changing geometry, size and the position of speculum, the microwave field of each point distributes and intensity in the orientable adjustment chamber, to adapt to the microwave sintering of large-size ceramic material goods.
Embodiment: the multimode cavity is the cylinder metal of ∮ 380mm * 380mm, and the minute surface of speculum 3 is the circular parabolic of ∮=100mm, and the inclination angle is 45 °.Adopt 2.45GHZ, the input of 1.5KW microwave source, the Sic ceramic material of sintering ∮ 80mm * 10mm is used the infrared radiometer thermometric.After starting microwave source, temperature rise to 2000 ℃ in ten minutes is incubated 10min then under this temperature.Maximum microwave uniform field can expand to the ∮ 100mm from the ∮ 30 of the former multimode cavity that do not have this reflection unit in the chamber.Sintered article density>95% shrinks uniformity, can't see any crackle.