阅读说明：本技术 一种基于LTCC技术的NiCuZn铁氧体制备方法 (Preparation method of NiCuZn ferrite based on LTCC technology ) 是由 冀欣然 孙美玲 周珂 郑辉 张阳 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种基于LTCC技术的NiCuZn铁氧体制备方法,包括以下步骤：(1)配料；(2)第一次球磨；(3)第一次烘干；(4)预烧；(5)掺杂；(6)第二次球磨；(7)第二次烘干；(8)造粒成型；(9)排胶；(10)烧结。本发明的基于LTCC技术的NiCuZn铁氧体制备方法,工艺条件易控制,成本低,通过Bi-(2)O-(3)和Co-(2)O-(3)的二元掺杂,可以得到致密度高,孔隙小,出色的磁性能的NiCuZn铁氧体,尤其是极大程度提高了饱和磁化强度,为低温烧结NiCuZn铁氧体提供了新的指导和思路,解决了如何兼顾低温烧结NiCuZn铁氧体材料的高磁导率,高饱和磁化强度,低损耗,温度稳定性的问题。(The invention discloses a preparation method of NiCuZn ferrite based on LTCC technology, which comprises the following steps: (1) preparing materials; (2) performing primary ball milling; (3) drying for the first time; (4) pre-burning; (5) doping; (6) performing secondary ball milling; (7) drying for the second time; (8) granulating and forming; (9) removing glue; (10) and (5) sintering. The preparation method of the NiCuZn ferrite based on the LTCC technology has the advantages of easily controlled process conditions and low cost, and Bi is used for preparing the ferrite 2 O 3 And Co 2 O 3 The binary doping can obtain NiCuZn ferrite with high density, small pores and excellent magnetic property, particularly greatly improves the saturation magnetization, provides new guidance and thinking for low-temperature sintering of the NiCuZn ferrite, and solves the problem of how to consider low densityThe high magnetic conductivity, high saturation magnetization, low loss and temperature stability of the temperature sintered NiCuZn ferrite material.)

1. A preparation method of NiCuZn ferrite based on LTCC technology is characterized by comprising the following steps:

(1) ingredients

With Fe₂O₃NiO, ZnO and CuO as raw materials according to the molecular formula (Ni)_0.28Cu_0.14Zn_0.58O)_1.03(Fe₂O₃)_0.97Calculating the mass percentage of each raw material, weighing the raw materials and uniformly mixing the raw materials to obtain the raw materials;

(2) first ball milling

According to the total mass of the raw materials, the zirconium balls of the ball mill and the alcohol, the raw materials and the alcohol are placed in a ball milling tank for wet ball milling according to the mass percentage ratio of 20-25% of the raw materials, 40-45% of the zirconium balls of the ball mill and 30-35% of the alcohol to obtain slurry;

(3) first drying

Drying the obtained slurry, and grinding to obtain powder;

(4) pre-firing

Placing the powder in a muffle furnace for presintering at the presintering temperature of 800-900 ℃ for 3 hours to obtain presintering powder;

(5) doping

Adding 0.3 percent of Bi into the pre-sintering powder material according to the mass of the pre-sintering powder material₂O₃And 0.2 to 0.8% of Co₂O₃Obtaining a doping material;

(6) second ball milling

According to the total mass of the doping material, the ball mill zirconium balls and the alcohol, the doping material and the alcohol are placed in a ball milling tank for wet ball milling according to the mass percentage ratio of 20-25% of the doping material, 40-45% of the ball mill zirconium balls and 30-35% of the alcohol to obtain NiCuZn slurry;

(7) second drying

Drying the obtained NiCuZn slurry, and grinding to obtain NiCuZn powder;

(8) granulating and forming

Taking a polyvinyl alcohol solution with the mass concentration of 8% as a binder, doping the polyvinyl alcohol solution into NiCuZn powder, wherein the mass of the doped binder is 5-10% of that of the NiCuZn powder, and uniformly mixing the polyvinyl alcohol solution and the NiCuZn powder in a mortar; placing the mixed NiCuZn powder in a mould to be pressed into a green body; grinding the green body into powder in a mortar, sieving the powder through 80-mesh and 140-mesh sieves, and taking the powder in the middle layers of the 80-mesh and 140-mesh sieves to obtain NiCuZn sieved powder with proper particle size; placing the NiCuZn screened powder in a mold, and pressing into a green body;

(9) glue discharging

Placing the green blank in a muffle furnace for calcining to remove PVA;

(10) sintering

And placing the green body after the binder removal in a muffle furnace, heating to 925 ℃, keeping for 10-15 h, and naturally cooling to room temperature to obtain the NiCuZn ferrite.

2. The method for preparing NiCuZn ferrite based on LTCC technology as claimed in claim 1, wherein in step (2), the ball milling time is at least 12 h.

3. The method for preparing NiCuZn ferrite based on LTCC technology as claimed in claim 1, wherein in step (6), the ball milling time is at least 12 h.

4. The preparation method of NiCuZn ferrite based on LTCC technology as claimed in claim 1, wherein in step (8), NiCuZn sieved powder is pressed into green body under pressure of 8-12 MPa.

5. The method for preparing NiCuZn ferrite based on LTCC technology as claimed in claim 1, wherein in step (9), the calcination temperature is 650 ℃ and the calcination time is 3 h.

6. The method for preparing NiCuZn ferrite based on LTCC technology as claimed in claim 1, wherein in step (10), the temperature rise rate is 5 ℃/min.

Technical Field

The invention relates to the field of electronic ceramic materials, in particular to a preparation method of NiCuZn ferrite based on LTCC technology.

Background

With the development of small size, Low cost, integration, portability and high performance of modern electronic devices, LTCC (Low Temperature Co-fired Ceramic) technology has been widely applied to magnetic devices and multilayer chip inductors. In the LTCC technology, because the LTCC is co-sintered with an Ag electrode, the sintering temperature needs to be reduced to below 961 ℃, so that the technical problem to be solved at present is to reduce the ferrite sintering temperature and keep good electromagnetic performance.

NiCuZn ferrite is more commercially available because it has a lower manufacturing cost than the remaining ferrites (e.g., LiZn ferrite). Meanwhile, NiCuZn ferrite ceramic has the properties of high magnetic permeability, small magnetic loss, good temperature stability and high resistivity, so that NiCuZn can have a good application prospect in a multilayer chip inductor, the requirement of an LTCC process that the sintering temperature is below 961 ℃ is met, but the sintering temperature is too low, the crystal grains are not completely grown, more pores exist in the internal structure of the ceramic, the density is low, the gaps are large, and the electromagnetic performance of the ferrite material is seriously limited.

Therefore, it is necessary to provide a solution to solve the above-mentioned drawbacks in the prior art.

Disclosure of Invention

The invention aims to solve the problems of the NiCuZn ferrite ceramic preparation method in the prior art, provides a NiCuZn ferrite preparation method based on the LTCC technology, is easy to operate, and solves the problems of high magnetic conductivity, high saturation magnetization, low loss and temperature stability of a low-temperature sintered NiCuZn ferrite material.

In order to achieve the purpose, the invention adopts the following technical scheme: a preparation method of NiCuZn ferrite based on LTCC technology comprises the following steps:

(1) ingredients

With Fe₂O₃NiO, ZnO and CuO as raw materials according to the molecular formula (Ni)_0.28Cu_0.14Zn_0.58O)_1.03(Fe₂O₃)_0.97Calculate eachWeighing the raw materials according to the mass percentage, and uniformly mixing to obtain the raw materials.

(2) First ball milling

The method comprises the following steps of putting raw materials and alcohol into a ball milling tank for wet ball milling to obtain slurry, wherein the raw materials, the ball milling zirconium balls and the alcohol are counted by the total mass of the raw materials, the ball milling zirconium balls and the alcohol, and the raw materials and the alcohol are mixed according to the mass percentage of 20-25% of the raw materials, 40-45% of the ball milling zirconium balls and 30-35% of the alcohol.

(3) First drying

And drying the obtained slurry, and grinding to obtain powder.

(4) Pre-firing

And placing the powder in a muffle furnace for presintering at the presintering temperature of 800-900 ℃ for 3 hours to obtain the presintering powder.

(5) Doping is carried out by adding 0.3 percent of Bi into the pre-sintering powder material according to the mass of the pre-sintering powder material₂O₃And 0.2 to 0.8% of Co₂O₃And obtaining the doping material.

(6) And (3) performing secondary ball milling, wherein the mass percentage of the doping material to be 20-25%, the mass percentage of the ball mill zirconium balls to be 40-45% and the mass percentage of the alcohol to be 30-35% are calculated by the total mass of the doping material, the ball mill zirconium balls and the alcohol, and placing the doping material and the alcohol into a ball milling tank for wet ball milling to obtain NiCuZn slurry.

(7) Second drying

And drying the obtained NiCuZn slurry, and grinding to obtain NiCuZn powder.

(8) Granulating and forming

Taking a polyvinyl alcohol solution with the mass concentration of 8% as a binder, doping the polyvinyl alcohol solution into NiCuZn powder, wherein the mass of the doped binder is 5-10% of that of the NiCuZn powder, and uniformly mixing the polyvinyl alcohol solution and the NiCuZn powder in a mortar; placing the mixed NiCuZn powder in a mould to be pressed into a green body; grinding the green body into powder in a mortar, sieving the powder through 80-mesh and 140-mesh sieves, and taking the powder in the middle layers of the 80-mesh and 140-mesh sieves to obtain NiCuZn sieved powder with proper particle size; and placing the NiCuZn screened powder in a mold, and pressing into a green body.

(9) Glue discharging

The green body was calcined in a muffle furnace to remove PVA.

(10) Sintering

And placing the green body after the binder removal in a muffle furnace, heating to 925 ℃, keeping for 10-15 h, and naturally cooling to room temperature to obtain the NiCuZn ferrite.

Preferably, in step (2), the ball milling time is at least 12 h.

Preferably, in step (6), the ball milling time is at least 12 h.

Preferably, in the step (8), the NiCuZn screened powder is pressed into a green body under the pressure of 8-12 MPa.

Preferably, in step (9), the calcination temperature is 650 ℃ and the calcination time is 3 hours.

Preferably, in the step (10), the temperature increase rate is 5 ℃/min.

Therefore, the invention has the following beneficial effects: the invention provides a preparation method of NiCuZn ferrite based on LTCC technology, which comprises the following steps of carrying out binary composite doping on NiCuZn ferrite: bi₂O₃And Co₂O₃The problems that NiCuZn ferrite growth crystal grains are not completely grown, the internal structure of the ceramic has more pores, the density is low, the gap is large and the like in the low-temperature sintering process are well solved; meanwhile, in order to meet the development of small size, low cost, integration, portability and high performance of the LTCC, the sintering temperature is effectively controlled below 961 ℃, and the excellent electromagnetic properties of the NiCuZn ferrite are kept, including high saturation magnetization and low coercive force; in the preparation method of the NiCuZn ferrite material based on the LTCC technology, NiCuZn with smaller particles is formed by ball milling twice and is pressed twice to form a green body, so that the uniformity of NiCuZn powder particles is ensured, the process conditions are easy to control, and the cost is low.

Drawings

FIG. 1 is an XRD pattern of NiCuZn ferrite prepared in example 1.

FIG. 2 is a hysteresis loop of NiCuZn ferrite prepared in example 1.

FIG. 3 is an XRD pattern of NiCuZn ferrite prepared in example 2.

FIG. 4 is a hysteresis loop of NiCuZn ferrite prepared in example 2.

FIG. 5 is an XRD pattern of NiCuZn ferrite prepared in example 3.

FIG. 6 is a hysteresis loop of NiCuZn ferrite prepared in example 3.

FIG. 7 is an XRD pattern of NiCuZn ferrite prepared in example 4.

FIG. 8 is a hysteresis loop of NiCuZn ferrite prepared in example 4.

FIG. 9 is an SEM photograph of NiCuZn ferrite prepared in examples 1, 2, 3 and 4.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

Example 1

(1) Ingredients

With Fe₂O₃NiO, ZnO and CuO as raw materials according to the molecular formula (Ni)_0.28Cu_0.14Zn_0.58O)_1.03(Fe₂O₃)_0.97Calculating the mass percentage of each raw material, weighing the raw materials and uniformly mixing the raw materials to obtain the raw materials;

(2) first ball milling

Putting the raw materials and alcohol into a ball milling tank for wet ball milling for 12h to obtain slurry according to the mass percentage ratio of 25% of the raw materials, 40% of the zirconium balls of the ball mill and 35% of the alcohol based on the total mass of the raw materials, the zirconium balls of the ball mill and the alcohol;

(3) first drying

Drying the obtained slurry, and grinding to obtain powder;

(4) pre-firing

Presintering the powder in a muffle furnace at the presintering temperature of 800 ℃ for 3 hours to obtain presintering powder;

(5) doping

Adding 0.3 percent of Bi into the pre-sintering powder material according to the mass of the pre-sintering powder material₂O₃And 0.2% of Co₂O₃Obtaining a doping material;

(6) second ball milling

Based on the total mass of the doping material, the ball mill zirconium balls and the alcohol, the doping material and the alcohol are placed in a ball milling tank for wet ball milling for 12 hours according to the mass percentage ratio of 20 percent of the doping material, 45 percent of the ball mill zirconium balls and 35 percent of the alcohol, and NiCuZn slurry is obtained;

(7) second drying

Drying the obtained NiCuZn slurry, and grinding to obtain NiCuZn powder;

(8) granulating and forming

Taking a polyvinyl alcohol solution with the mass concentration of 8% as a binder, doping the polyvinyl alcohol solution into NiCuZn powder, wherein the mass of the doped binder is 5-10% of that of the NiCuZn powder, and uniformly mixing the polyvinyl alcohol solution and the NiCuZn powder in a mortar; placing the mixed NiCuZn powder in a mould to be pressed into a green body; grinding the green body into powder in a mortar, sieving the powder through 80-mesh and 140-mesh sieves, and taking the powder in the middle layers of the 80-mesh and 140-mesh sieves to obtain NiCuZn sieved powder with proper particle size; putting the NiCuZn screened powder into a mold, and pressing the powder into a green body under the pressure of 10 MPa;

(9) glue discharging

Placing the green blank in a muffle furnace, calcining at 650 ℃ for 3h, and removing PVA;

(10) sintering

And (3) placing the green body after the glue removal into a muffle furnace, heating to 925 ℃ at a heating rate of 5 ℃/min, keeping for 10 hours, and then naturally cooling to room temperature to obtain the NiCuZn ferrite.

The XRD pattern of NiCuZn ferrite prepared in example 1 is shown in FIG. 1. As can be seen from fig. 1, example 1 succeeded in preparing a pure-phase NiCuZn ferrite.

The hysteresis loop of the NiCuZn ferrite prepared in example 1 is shown in FIG. 2. As can be seen from FIG. 2, the saturation magnetization of NiCuZn ferrite was 52.256emu/g, and the coercive force was 1.7365 Oe.

Example 2

(1) Ingredients

With Fe₂O₃NiO, ZnO and CuO as raw materials according to the molecular formula (Ni)_0.28Cu_0.14Zn_0.58O)_1.03(Fe₂O₃)_0.97Calculating the mass percentage of each raw material, weighing the raw materials and uniformly mixing the raw materials to obtain the raw materials;

(2) first ball milling

According to the total mass of the raw materials, the zirconium balls of the ball mill and the alcohol, the raw materials and the alcohol are placed in a ball milling tank for wet ball milling for 12 hours according to the mass percentage ratio of 25% of the raw materials, 45% of the zirconium balls of the ball mill and 30% of the alcohol to obtain slurry;

(3) first drying

Drying the obtained slurry, and grinding to obtain powder;

(4) pre-firing

Presintering the powder in a muffle furnace at the presintering temperature of 900 ℃ for 3 hours to obtain presintering powder;

(5) doping

Adding 0.3 percent of Bi into the pre-sintering powder material according to the mass of the pre-sintering powder material₂O₃And 0.4% of Co₂O₃Obtaining a doping material;

(6) second ball milling

Based on the total mass of the doping material, the ball mill zirconium balls and the alcohol, the doping material and the alcohol are placed in a ball milling tank for wet ball milling for 12 hours according to the mass percentage ratio of 25 percent of the doping material, 45 percent of the ball mill zirconium balls and 30 percent of the alcohol, and NiCuZn slurry is obtained;

(7) second drying

Drying the obtained NiCuZn slurry, and grinding to obtain NiCuZn powder;

(8) granulating and forming

Taking a polyvinyl alcohol solution with the mass concentration of 8% as a binder, doping the polyvinyl alcohol solution into NiCuZn powder, wherein the mass of the doped binder is 5-10% of that of the NiCuZn powder, and uniformly mixing the polyvinyl alcohol solution and the NiCuZn powder in a mortar; placing the mixed NiCuZn powder in a mould to be pressed into a green body; grinding the green body into powder in a mortar, sieving the powder through 80-mesh and 140-mesh sieves, and taking the powder in the middle layers of the 80-mesh and 140-mesh sieves to obtain NiCuZn sieved powder with proper particle size; putting the NiCuZn screened powder into a mold, and pressing the powder into a green body under the pressure of 8 MPa;

(9) glue discharging

Placing the green blank in a muffle furnace, calcining at 650 ℃ for 3h, and removing PVA;

(10) sintering

And (3) placing the green body after the glue removal into a muffle furnace, heating to 925 ℃ at a heating rate of 5 ℃/min, keeping for 12 hours, and then naturally cooling to room temperature to obtain the NiCuZn ferrite.

The XRD pattern of NiCuZn ferrite prepared in example 2 is shown in FIG. 1. As can be seen from fig. 3, example 2 succeeded in preparing a pure-phase NiCuZn ferrite.

The hysteresis loop of the NiCuZn ferrite prepared in example 2 is shown in FIG. 2. As can be seen from FIG. 4, the saturation magnetization of NiCuZn ferrite was 60.014emu/g, and the coercive force was 0.41302 Oe.

Example 3

(1) Ingredients

With Fe₂O₃NiO, ZnO and CuO as raw materials according to the molecular formula (Ni)_0.28Cu_0.14Zn_0.58O)_1.03(Fe₂O₃)_0.97Calculating the mass percentage of each raw material, weighing the raw materials and uniformly mixing the raw materials to obtain the raw materials;

(2) first ball milling

According to the total mass of the raw materials, the zirconium balls of the ball mill and the alcohol, the raw materials and the alcohol are placed in a ball milling tank for wet ball milling for 12 hours according to the mass percentage ratio of 20% of the raw materials, 45% of the zirconium balls of the ball mill and 35% of the alcohol, and slurry is obtained;

(3) first drying

Drying the obtained slurry, and grinding to obtain powder;

(4) pre-firing

Presintering the powder in a muffle furnace at the presintering temperature of 850 ℃ for 3 hours to obtain presintering powder;

(5) doping

Adding 0.3 percent of Bi into the pre-sintering powder material according to the mass of the pre-sintering powder material₂O₃And 0.6% of Co₂O₃Obtaining a doping material;

(6) second ball milling

Based on the total mass of the doping material, the ball mill zirconium balls and the alcohol, the doping material and the alcohol are placed in a ball milling tank for wet ball milling for 12 hours according to the mass percentage ratio of 25 percent of the doping material, 45 percent of the ball mill zirconium balls and 30 percent of the alcohol, and NiCuZn slurry is obtained;

(7) second drying

Drying the obtained NiCuZn slurry, and grinding to obtain NiCuZn powder;

(8) granulating and forming

Taking a polyvinyl alcohol solution with the mass concentration of 8% as a binder, doping the polyvinyl alcohol solution into NiCuZn powder, wherein the mass of the doped binder is 5-10% of that of the NiCuZn powder, and uniformly mixing the polyvinyl alcohol solution and the NiCuZn powder in a mortar; placing the mixed NiCuZn powder in a mould to be pressed into a green body; grinding the green body into powder in a mortar, sieving the powder through 80-mesh and 140-mesh sieves, and taking the powder in the middle layers of the 80-mesh and 140-mesh sieves to obtain NiCuZn sieved powder with proper particle size; putting the NiCuZn screened powder into a mold, and pressing the powder into a green body under the pressure of 12 MPa;

(9) glue discharging

Placing the green blank in a muffle furnace, calcining at 650 ℃ for 3h, and removing PVA;

(10) sintering

And (3) placing the green body after the glue removal into a muffle furnace, heating to 925 ℃ at a heating rate of 5 ℃/min, keeping for 15h, and then naturally cooling to room temperature to obtain the NiCuZn ferrite.

The XRD pattern of NiCuZn ferrite prepared in example 3 is shown in FIG. 5. As can be seen from fig. 5, example 3 succeeded in preparing a pure-phase NiCuZn ferrite.

The hysteresis loop of the NiCuZn ferrite prepared in example 3 is shown in FIG. 6. As can be seen from FIG. 6, the saturation magnetization of NiCuZn ferrite was 55.858emu/g, and the coercive force was 4.8712 Oe.

Example 4

(1) Ingredients

With Fe₂O₃NiO, ZnO and CuO as raw materials according to the molecular formula (Ni)_0.28Cu_0.14Zn_0.58O)_1.03(Fe₂O₃)_0.97Calculating the mass percentage of each raw material, weighing the raw materials and uniformly mixing the raw materials to obtain the raw materials;

(2) first ball milling

According to the total mass of the raw materials, the zirconium balls of the ball mill and the alcohol, the raw materials and the alcohol are placed in a ball milling tank for wet ball milling for 12 hours according to the mass percentage ratio of 25% of the raw materials, 45% of the zirconium balls of the ball mill and 35% of the alcohol, and slurry is obtained;

(3) first drying

Drying the obtained slurry, and grinding to obtain powder;

(4) pre-firing

Presintering the powder in a muffle furnace at the presintering temperature of 800 ℃ for 3 hours to obtain presintering powder;

(5) doping

Adding 0.3 percent of Bi into the pre-sintering powder material according to the mass of the pre-sintering powder material₂O₃And 0.8% of Co₂O₃Obtaining a doping material;

(6) second ball milling

Based on the total mass of the doping material, the ball mill zirconium balls and the alcohol, the doping material and the alcohol are placed in a ball milling tank for wet ball milling for 12 hours according to the mass percentage ratio of 25 percent of the doping material, 40 percent of the ball mill zirconium balls and 35 percent of the alcohol, and NiCuZn slurry is obtained;

(7) second drying

Drying the obtained NiCuZn slurry, and grinding to obtain NiCuZn powder;

(8) granulating and forming

Taking a polyvinyl alcohol solution with the mass concentration of 8% as a binder, doping the polyvinyl alcohol solution into NiCuZn powder, wherein the mass of the doped binder is 5-10% of that of the NiCuZn powder, and uniformly mixing the polyvinyl alcohol solution and the NiCuZn powder in a mortar; placing the mixed NiCuZn powder in a mould to be pressed into a green body; grinding the green body into powder in a mortar, sieving the powder through 80-mesh and 140-mesh sieves, and taking the powder in the middle layers of the 80-mesh and 140-mesh sieves to obtain NiCuZn sieved powder with proper particle size; putting the NiCuZn screened powder into a mold, and pressing the powder into a green body under the pressure of 10 MPa;

(9) glue discharging

Placing the green blank in a muffle furnace, calcining at 650 ℃ for 3h, and removing PVA;

(10) sintering

And (3) placing the green body after the glue removal into a muffle furnace, heating to 925 ℃ at a heating rate of 5 ℃/min, keeping for 10 hours, and then naturally cooling to room temperature to obtain the NiCuZn ferrite.

The XRD pattern of NiCuZn ferrite prepared in example 4 is shown in FIG. 7. As can be seen from fig. 7, example 4 succeeded in producing a pure phase NiCuZn ferrite.

The hysteresis loop of NiCuZn ferrite prepared in example 4 is shown in FIG. 8. As can be seen from FIG. 8, the saturation magnetization of NiCuZn ferrite was 51.891emu/g, and the coercive force was 4.9175 Oe.

SEM images of NiCuZn ferrites prepared in examples 1, 2, 3 and 4 are shown in (a) (b) (c) (d) of FIG. 9.

As is clear from FIG. 9, Bi of the same mass as that of the powder was added in examples 1, 2, 3 and 4₂O₃And Co of different masses₂O₃The NiCuZn ferrite ceramic material with good compactness and small pores and different Co are obtained₂O₃The average size of the samples is shown to follow the Co₂O₃The additive is increased and slightly reduced because of the high melting point of Co₂O₃The additives may hinder grain growth and densification. Thus, the invention is shown by Bi₂O₃And Co₂O₃The binary doping can obtain the NiCuZn ferrite with high density, small pores and excellent magnetic property, particularly greatly improves the saturation magnetization, and provides new guidance and thinking for low-temperature sintering of the NiCuZn ferrite.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.