Siliceous composition and method for obtaining same
A powdery composition based on silica for ceramic welding, in particular by projection, comprising from 10 to 90% of a phase of siliceous particles comprise at least 80% by weight of cristobalite and at most 15% by weight of tridymite, based on the total weight of the composition, from 90 to 10% by weight of conventional additives forming a binding phase, based on the total weight of the composition, said siliceous particles having a d 50 comprised between 350 and 800 μm, preferably between 400 and 500 μm.
1. A method for preparing a powdery composition based on silica for ceramic welding, comprising the steps:
(a) preparing a phase of siliceous particles comprising at least 80% by weight of cristobalite and at most 20% by weight of tridymite, based on the total weight of the phase of siliceous particles; and
(b) mixing said phase of siliceous particles with one or more additives forming a binding phase in ceramic welding,
said step for preparing said phase of siliceous particles comprising a supply of quarry quartz sand particles having a d 50 comprising between 350 and 800 μm in a rotary furnace attaining 1,400° C. to 1,500° C. in an area called the hottest area and for baking for a predetermined period of time with said phase of siliceous particles being obtained.
2. The preparation method according to claim 1 , wherein said quarry quartz sand particles have a d 5 max of 1,100 μm.
3. The preparation method according to claim 1 , wherein said quarry quartz sand particles have a d 5 min of 150 μm.
4. The preparation method according to claim 1 , wherein said quarry quartz sand particles have before baking an SiO 2 content greater than or equal to 97 by weight, based on the total weight of quarry quartz sand particles.
5. The preparation method according to claim 1 , wherein the area called the hottest area has a temperature greater than or equal to 1,430° C.
6. The preparation method according to claim 1 , wherein said siliceous particles have a d 3 max of 1,100 μm.
7. The preparation method according to claim 1 , wherein said siliceous particles have a d 3 min of 150 μm.
8. The preparation method according to claim 1 , wherein said siliceous particles have an SiO 2 content greater than or equal to 97% by weight, based on the total weight of siliceous particles.
9. The preparation method according to claim 1 , wherein said phase of siliceous particles comprises at least 80% by weight of cristobalite and at most 15% by weight of tridymite, based on the total weight of siliceous particles.
10. The preparation method according claim 1 , wherein, during said mixing step, 20 to 85% by weight of phase of siliceous particles and 80 to 15% by weight of binding phase, based on the total weight of the composition, are brought into a mixing tank.
11. The preparation method according to claim 1 , wherein, during said mixing step, 50 to 85% by weight of phase of siliceous particles and 50 to 15% by weight of binding phase, based on the total weight of the composition, are brought into a mixing tank.
12. The preparation method according to claim 1 , wherein said binding phase comprises at least one of the following elements or compounds: Al, Si, Mg, Ca, Fe, Cr, Zr, Al 2 O 3 , SiO 2 , MgO, CaO, Fe 2 O 3 , Cr 2 O 3 , ZrO 2 , CaO 2 , MgO 2 , BaO 2 , and SrO 2 .
13. The preparation method according to claim 12 , wherein said binding phase comprises at least one of the elements or compounds selected from the group consisting of CaO, MgO, and xCaO.yMgO, wherein the x and y represent mass fractions for which x+y<100.
14. The preparation method according to claim 12 , wherein said binding phase comprises at least MgO.