BRPI1005268A2 - sintered ceramic material, process for its production, and its use in ballistic armor - Google Patents

Abstract

SINTERED CERAMIC MATERIAL, PROCESS FOR PRODUCTION, AND ITS USE IN BALLISTIC SHIELDING The present invention describes a sintered ceramic material composed of alumina and niobium oxide, which when sintered is capable of improving the material's ballistic properties, making it useful for vehicle armor and other equipment. The present invention further describes a process for producing the material.

Description

Descriptive Report of Invention Patent

Sintered Ceramic Material, Process for Your Production, is your Use in Ballistic Shielding

Field of Invention

The present invention describes a sintered ceramic material, composed of alumina and niobium oxide, which when sintered is capable of improving the ballistic properties of the material, making it particularly Citil for shielding impacted vehicles and equipment. The present invention also discloses a process for producing said material.

Background of the Invention

During the last years, a lot of effort has gone into the search for ceramic materials, with smaller masses than metals, with more suitable shielding and shielding applications where weight matters, as in aircraft and for the human body. Some of these efforts aimed to use silicon carbide as a candidate, while others used fiber-reinforced ceramic materials.

EP 199 459 describes ceramics alloys having high strength, where the alloy comprises Zr and / or Hf oxides combined with metal niobates and / or tantalates.

US 6,218,324 describes a ceramic composition comprising a ceramic matrix a material of the formula ABO4, where A is a dative cation and B is tungsten or molybdenum, dispersed in the ceramic matrix, creating a weak interface with the matrix and ο material.

US 7,297,646 describes glasses and vitroceramics comprising niobium or tantalum oxide with a combination of alumina, Zr or Hf oxides and / or rare earth metals.

US 2007/105706 describes the use of carbides such as boron, silicon, tantalum, zirconium, hafnium and tungsten and a boride of

group IVa Va or Via of the periodic table. None of the previous known efforts have been found satisfactory, so the search for ceramic materials remains.

The present invention differs from known prior art documents, among other reasons, in that it describes aluminum niobate-coated alumina grains, which grains have improved ballistic properties.

Summary of the Invention

It is an object of the invention to provide a sintered ceramic material composed of alumina and niobium oxide. Said material has remarkable hardness and / or impact absorption properties, being Citil, among others, for ballistic applications.

In a preferred embodiment, the ceramic material of the invention comprises alumina and 3-5% w / w niobium oxide. In a preferred embodiment, the ceramic material of the invention comprises aluminum niobate deposited around the alumina grains.

And a further object of the present invention is a process for preparing a sintered ceramic material comprising the steps of: preparing a niobium oxide alumina mixture; adding a sintering additive;

-mould the material into the desired shape; and sintering the material.

In a preferred embodiment, the proportion of said mixture is 95-97% w / w alumina at ρό and 3-5% w / w niobium oxide at ρό. In a preferred embodiment, said sintering additive is added at a ratio of 1.5% w / w total mixture. In a preferred embodiment, the alumina and niobium oxide mixture is ground in water, subsequently oven dried and then deagglomerated and / or sieved prior to the molding and sintering steps. Preferably, the step of sintering the material is conducted at a temperature in the range of 1400 ° C to 1450 ° C for a time from 1h to 3h, after which such material is cooled. It is another object of the present invention to provide the use of a sintered ceramic material composed of alumina and niobium oxide in the preparation of ballistic armor.

These and other objects of the invention will be immediately appreciated by those skilled in the art and will be described in more detail below.

Brief Description of the Figures

FIGURE 1 shows a conventional non-niobium alumina-based ceramic material with predominantly transgranular fracture surface (sample # 1).

FIGURE 2 shows a conventional non-nibia alumina-based ceramic, with intergranular fracture surface (sample # 2) due to poor sintering.

FIGURE 3 shows a preferred embodiment of predominantly intergranular fracture surface ceramic (sample # 3) by the effect of the addition of niobia to alumina.

FIGURE 4 shows a target with 7.62 mm projectile impacted ceramic material.

Detailed Description of the Invention

The ceramic material of the invention is sintered and composed of alumina and niobium oxide. Said material has remarkable hardness and / or impact absorption properties, being, among others, for ballistic applications. In a preferred embodiment, the ceramic material of the invention comprises alumina and 3-5% w / w niobium oxide. In a preferred embodiment, the ceramic material of the invention comprises aluminum niobate deposited around the alumina grains.

The invention process for preparing sintered ceramic material comprises the steps of:

preparing a niobium oxide alumina mixture;

adding a sintering additive; -mould the material into the desired shape; and sintering the material.

In a preferred embodiment, the proportion of said mixture is 95-97% w / w alumina at ρό and 3-5% w / w niobium oxide at ρό. In a preferred embodiment, said sintering additive is added at a ratio of 1.5% w / w total mixture. In a preferred embodiment, the alumina and niobium oxide mixture is ground in water, subsequently oven dried and then deagglomerated and / or sieved prior to the molding and sintering steps. Preferably, the step of sintering the material is conducted at a temperature in the range of 1400 ° C to 1450 ° C for a time from 1h to 3h, after which such material is cooled.

The inventive material is particularly Citil for the preparation of high magnitude solid impact resistant surfaces, especially ballistic armor. The examples described herein are intended merely to exemplify some of the many ways of carrying out the invention and should not be construed as restrictive but as illustrative. Sintered Ceramic Material

In a preferred embodiment, the sintered ceramic material of the present invention comprises 95-97% w / w alumina and 3-5% w / w niobium oxide. It also has aluminum niobate deposited around the alumina grains, thus improving its ballistic properties. Preparation Process

In a preferred embodiment of the invention, the process for preparing sintered ceramic material comprises the steps of:

a) prepare a mixture of 95-97% w / w alumina in ρό and 3-5% w / w of

niobium oxide in ρό;

b) adding 1.5% w / w total of the mixture of a) of a sintering additive;

c) milling the mixture in water; d) oven drying;

e) deagglomerating and / or sieving dry material;

F) shaping the material into the desired shape;

g) sintering the material at a temperature in the range of 1400 ° C to 1450 ° C for a time from 1h to 3h.

h) cool the material.

In a preferred embodiment, the sintering additive used is

polyethylene glycol (PEG).

The importance of the addition of niobia to alumina is that niobia reacts with alumina, forming aluminum niobate (AINbO4) 1 that deposits on the grain boundaries of alumina. This increases the energy absorption of the ceramic material in these grain boundaries and improves its ballistic protection properties. Use in preparation of ballistic barriers

The ceramic material of the invention was used directly as a ballistic protection material. Ballistic tests with different ceramic materials of the invention were conducted and demonstrated superior ballistic protection properties than conventional sintered alumina (without ceramic additions and sintered at or above 1600 ° C for a minimum time of 1h). In addition to the high ballistic protection properties of the ceramic material, its sintering occurs at temperatures (range 1400 ° C to 1450 ° C) lower than conventional temperatures (equal to or greater than 1600 ° C), which provides a lower waste of as well as the cost of sintering furnaces for obtaining sintered ceramic material, increasing its economic viability.

Table 1 shows three different ceramic compositions and sintering conditions. Compositions # 1 and # 2 are conventional and composition # 3 is a preferred embodiment of the invention. Table 1

Compositions AI2O3 Nb2O5 Sintering Time Temperature analyzed%% sintering (° C) (hours) # 1 100 0 1600 1 # 2 100 0 1400 3 # 3 96.00 4 1400 3

Table 2 shows the results obtained for physical properties.

shielding and ballistic test results:

kinetic energy and predominant mechanism of fracture in the ballistic impact of

7.62 mm projectile, used in rifles. Composition # 3 featured the best

results, and corresponds to the percentage range of alumina and niobia in the

ceramic, having been the one that showed the best results in the ballistic tests.

Table 2

Tested compositions Hardness Vickers Density (%) Longitudinal wave velocities Energy absorption (%) Fracture mechanism # 1 1261 ± 58 84.2 ± 2.2 7157.1 m / s 72.4 Trgnsgranulgr # 2 242 土 23 64.5 ± 2.4 3577.2 m / s 53.0 Intergranular # 3 1319 ± 135 87.2 ± 2.4 7921.9 m / s 93.1 I 门 tcrgra 门 ulgr

Table 2 shows that the hardness, densification, longitudinal wave velocity, and energy absorption at the ballistic impact for the # 3 'alumina composition with 4% sintered niobium adjoining at 1400 ° C for 3 hours has values significantly. higher than the other compositions analyzed. The low result values for sample # 2 are due to poor

sintering of pure alumina at a temperature of 1400 ° C, which increases when the sintering temperature is raised, or when niobia is added to 1400 ° C. In composition # 3, the formation of a second phase occurs in the grain contours of alumina, aluminum niobate, while the grain interior remains with high density and hardness. Aluminum niobate AINbO4 has a lower hardness than alumina, which promotes an intergranular fracture tendency associated with increased energy absorption of the projectile by the ceramic in the fracture caused by ballistic impact. Subsequent ballistic tests with ceramic materials subjected to impact of 0.50 piercing projectile at 25 m distance and velocity of 900 m / s ， had excellent results. The ceramic material of the invention (according to sample # 3), sintered in piano format, was placed on a base (a block) of aluminum. With the impact of the projectile in such conditions, there was rupture of the ceramic shield and little penetration of the aluminum block. On the other hand, the ceramic material of the invention (according to sample # 3), sintered in concave-convex shape, was placed on a base (a block) of aluminum. Even with the impact of the projectile under such conditions, the aluminum block was not damaged. These data demonstrate the high potential of the inventive material for use in ballistic armor.

Those skilled in the art will immediately appreciate the teachings provided herein and will readily understand that minor variations in the embodiments of the invention are possible and should be considered as falling within the scope of the invention and the appended claims.

Claims (10)

Sintered Ceramic Material, Process。for Your Production, Its Use in Ballistic Shielding 1. Ceramic material comprising sintered niobium alumina and oxide. Ceramic material according to claim 1, characterized in that it comprises alumina and 3-5% w / w niobium oxide. Ceramic material according to claim 1 or 2, characterized in that it comprises aluminum niobate deposited around the alumina grains. A process for preparing a ceramic material comprising the steps of: preparing a mixture of alumina and niobium oxide; adding a sintering additive; -mould the material into the desired shape; and sintering the material. Process according to Claim 4, characterized in that the proportion of said mixture is 95-97% w / w alumina at ρό and 3-5% w / w niobium oxide at ρό. Process according to Claim 4 or 5, characterized in that said sintering additive is added in the proportion of 1.5% w / total weight of the mixture. Process according to any one of claims 4-6, characterized in that said additive is PEG. Process according to any one of claims 4-7 ', characterized in that the mixture of alumina and niobium oxide is ground in water, subsequently oven dried and then deagglomerated and / or sieved prior to the molding and sintering steps. Process according to any one of claims 4-8, characterized in that the step of sintering the material is conducted at a temperature in the range of 1400 ° C to 1450 ° C for a time from 1h to 3h. 10. Use of sintered ceramic material composed of alumina and niobium oxide characterized for the preparation of ballistic shields.