Untitled record

Gadolinium Oxide-Doped Zirconium Oxide Overcoat and/or

Method of Making the Same

Full description

Background of the invention

Some representative embodiments of the invention relate to a coated product including at least one infrared (IR) reflecting layer of a material such as silver or the like in a low-E coating. In some embodiments, at least one layer of the coating is, or includes zirconium oxide (e.g., ZrOx) which may be doped with gadolinium (Gd)-doped and/or gadolinium oxide (e.g., GdxOy). In some exemplary embodiments, advantageously, providing a coating comprising zirconium oxide doped with gadolinium (Gd) produces a coating with lower fatigue and better durability. When a gadolinium (Gd) doped zirconium oxide layer is provided as the top layer or topcoat for the coated object (e.g., over a silicon nitride-based layer), this results in improved durability, chemical and heat stability of the coating, in some exemplary embodiments. However, in some representative embodiments, the durability of the coated product can be improved where needed. Objects coated herein may be used in the context of insulating glass (IG) window units, vehicle windows, or in other suitable applications such as bay window applications, laminated windows, and/or the like.

Coated objects are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, bay windows, etc. In some representative cases, designers of coated objects typically seek a combination of high visible transmittance, low emissivity (or low emissivity), and/or low plate resistance (Rs). The high visible transmittance can allow the use of coated objects in applications where such features are preferable, for example, in architectural or vehicular window applications, while the low panel impedance features allow such coated objects to block significant amounts of IR radiation so that, for example, Reduce unwanted heating of vehicle or building interiors. Thus, typically, for coatings used on architectural glass to block large amounts of IR radiation, high transmittance in the visible spectrum is usually preferred. However, low transmission and/or high reflectance in the IR and/or near-IR part(s) of the spectrum are also preferred, to reduce, for example, unwanted heating in vehicle or building interiors.

In some representative embodiments, a topcoat of low-E coating, etc. may be provided to increase durability.

However, in some cases, these overcoatings can undergo stress when deposited, or undergo stress after heating, or during heat treatment, heat bending, heat strengthening, etc.

In some cases, stress from these overcoatings can negatively affect the overall durability of the coating. For this, it may sometimes be preferable to provide a window unit or other glazing body with a more durable topcoat.

General description of the invention

In light of the above, it can be realized in the art that there is a need in the art for a layer and/or topcoating that can be included in and/or on a low-E stack to increase the overall durability of the coated product. Certain representative embodiments of this invention relate to a coated product that is durable, has increased thermal stability, and has a reduced impact on optical features. Certain representative embodiments of the present invention also relate to the method of preparing them.

Particular representative embodiments of the invention relate to a coated product comprising a substrate that supports a multi-layer coating over a large surface thereof. The coating includes a low-E coating and a layer comprising gadolinium (Gd)-doped zirconium oxide, potentially in contact with the low-E coating. The low-E coating, when moving away from the substrate, comprises: a first insulating layer, an infrared (IR) reflecting layer including silver, and a second insulating layer. The layer includes zirconium oxide doped with gadolinium (Gd), from 1 to 20% Gd.

Some representative embodiments of the invention relate to a coated product comprising a functional coating applied to a large surface of a glass substrate. A topcoat is provided over the functional paint and/or the outer layer of the functional paint. The topcoat layer includes zirconium oxide doped with gadolinium (Gd).

According to some representative embodiments, the coated product is heat treated with paint. According to some exemplary embodiments, the coating has a net compressive residual stress after heat treatment and has a lower tensile stress compared to a coating without gadolinium (Gd) doped in the layer comprising gadolinium (Gd)-doped zirconium oxide. According to some exemplary embodiments, the topcoat layer undergoes fewer phase changes during heat treatment than a topcoat layer without the gadolinium (Gd) dopant.

Some representative embodiments of the invention relate to a method of preparing a coated product comprising a coating supported on a glass substrate. A first insulating layer is placed, directly or indirectly, on the glass substrate. An infrared (IR) reflecting layer is placed on the first insulating layer. A second insulating layer is applied over the infrared (IR) reflective layer. A topcoat layer comprising zirconium oxide doped with gadolinium is spray-deposited on the second insulating layer, the topcoat layer being the outer layer of the coating. The glass substrate is heat treated with a coating applied to it. The topcoat layer contains from about 1 to 20% Gd.

Some representative embodiments of the invention relate to a method of preparing a coated product comprising a coating supported on a glass substrate. A glass substrate is provided. A functional layer is applied, directly or indirectly, to a glass substrate, and the functional layer is an infrared (IR) reflective layer. A topcoat layer comprising gadolinium-doped zirconium oxide is spray-deposited on the second buffer layer, the topcoat layer being the outer layer of the coating and containing from about 1 to 20% Gd. The glass substrate can be heat treated with the coating on it. The coating has a lower net compressive residual stress and tensile stress compared to a coating without the gadolinium (Gd) dopant in the overcoating layer.

The attributes, characteristics, advantages and representations described herein may be combined to create other models.

Brief explanation of the drawings

These and other features and advantages can be understood better and more comprehensively by referring to the following detailed description of representational models in combination with figures, where:

Figure 1: A diagram of the different phases of zirconium oxide, showing the structure of zirconium oxide flakes/layers before and after heating.

Figure 2: A graph showing the stress in a pure (ie, undoped) zirconium oxide layer, coated, and after heating.

Figure 3: A cross-sectional view of a low-E coating with a topcoat thereon according to some representative embodiments of the invention.

Figure 4 is a cross-sectional view of a coating comprising an infrared (IR) reflecting layer based on nickel and/or nickel chromium with a gadolinium (Gd)-doped zirconium oxide based topcoat according to some representative embodiments of the invention.

Figure 5 is a cross-sectional view of a coating comprising dual infrared reflective layers with a zirconium oxide-based topcoat doped with gadolinium (Gd) according to some representative embodiments of the invention.

Figure 6 is a cross-sectional view of a coating including a gadolinium (Gd)-doped zirconium oxide-based topcoat according to some representative embodiments of the invention.

Detailed description

Referring now more specifically to the attached figures, where identical reference numbers indicate identical parts in each of the several figures.

Some representative embodiments of the present invention relate to a coated product including a zirconium oxide-based topcoat doped with gadolinium (Gd), and/or a method of preparing it. According to some exemplary embodiments, a gadolinium (Gd) doped zirconium oxide-based topcoat is provided that can be hardened/heat-cured.

As explained above, low-E coatings etc. are widely used in window applications such as insulating glass (IG) window units, vehicle windows, bay windows, etc. These coatings are sometimes susceptible to damage in certain situations, for example, from the environment, handling, and/or subjecting the coating to heat treatment etc.

Furthermore, the overall durability of the coating can be compromised as a result of the high temperatures to which the coated product can be exposed during the heat-curing process, especially when a single layer in the coating is subject to fatigue, phase changes, or instability after heating. Therefore, there are disadvantages associated with heat treating special coatings, and such coatings have layers, in some representative embodiments.

Layers based on zirconium oxide can be used as a topcoat in low-E coatings, etc. However, the presence of multiple phases and phase changes during heat treatment of zirconium-based wafers can cause durability issues and in the entire stack due to, for example, possible volume expansions and stresses in the zirconium oxide-based layer.

Zirconium oxide can crystallize in three different forms, namely volumetric, tetragonal, and monoclinic. In some cases, the composition of the particular phase depends on the conditions of the coating process. The monoclinic phase is generally stable at ambient temperatures, the tetragonal phase is generally stable between 1200 and 2370°C, and the cubic phase is generally stable at still-high temperatures. Sometimes it may be possible to have several phases, such as tetrahedral and cubic, simultaneously. These phases and their peaks are depicted in Figure 1.

Figure 1 shows the structure of the zirconium oxide wafer before and after heating. According to Figure 1, the zirconium oxide wafer is crystalline before and after heating/heat treatment. The monoclinic phase of zirconium oxide predominates, except for one peak of the tetragonal phase at 2theta of 30.224° in the heat-treated zirconium oxide wafer scan.

“Pure” zirconium oxide was used as a topcoat in a low-E stack. For example, see U.S. Patent No. 7,217,461, the entire contents of which are incorporated by reference herein. However, when pure zirconium oxide topcoats are used in the coating, the thermal stability and durability of the coating can be reduced.

As mentioned above, in some cases, the simultaneous presence of several phases and phase changes during heating processes used for zirconium oxide wafers can cause durability issues (e.g., low toughness) in layers based on “pure” zirconium oxide (on For example, layers consisting mainly of zirconium oxide (such as layers where zirconium oxide is not separately doped). This reduced durability can also affect an overall coating that includes a layer (or layers) based on zirconium oxide. For example, the durability of the layer(s) and/or coating may be compromised due to volume expansions and/or stresses arising, in some cases, from exposure to temperatures at which heat treatment is typically performed.

Furthermore, using pure zirconium oxide as a layer and/or topcoating layer in a low-E stack can cause the wafer to be subjected to high compressive stress, upon coating. Figure 2 shows the stress in a zirconium oxide wafer without doping agent/stabilizing agent before and before heat treatment. In some representative embodiments, after heating, the stress in a dissimilar zirconium oxide based layer (e.g., a layer without a stabilizer) changes from compressive to tensile. In some special representative embodiments, the stress may be residual; For example, compressive residual stress, tensile residual stress, and/or etc.

When compressive stress is applied, it acts toward the center of a material. Therefore, when a material is subjected to compressive stress, the material is under compression. When a material is subjected to tensile stress, on the one hand, the material may experience stretching or elongation. Therefore, if there is too much tensile stress in a layer in a coating, the layer and/or coating can suffer deformation, cracking, and/or other types of degradation in some cases. Therefore, in some representative embodiments, it may be preferable for the coating to have a compressive stress rather than a tensile stress.

To overcome these issues, the zirconium oxide layer can be doped with gadolinium and/or gadolinium oxide (e.g., Gd and/or GdxOy as Gd2O3).

Surprisingly, it has been discovered that when a zirconium oxide substrate is doped with gadolinium and/or gadolinium oxide (e.g., Gd and/or GdxOy such as Gd2O3), the stability of the high-temperature phase of zirconium oxide can be improved. In some exemplary embodiments, a zirconium oxide based layer similar to Gd may be used as a topcoat in a low-E coating. In some exemplary embodiments, when doped with gadolinium, a zirconium oxide substrate can be more stable, especially at higher temperatures. In other representative embodiments, layer voltages based on zirconium oxide similar to Gd can be better controlled.

In some exemplary embodiments, when the overcoating of a low-E stack is made of, or consists of, zirconium oxide doped with gadolinium (Gd)-doped, the entire coating can be subjected to improved durability and thermal stability at high temperature. In some cases, the surface structure and appearance of the wafer can be beneficially improved, compared to undoped zirconium oxide, or even zirconium oxide doped with other materials. This is especially true at higher temperatures.

For example, when a coating is subjected to a hardening and/or heat treatment process, the heat can cause changes in the structural and morphological properties of the coating. Surprisingly, in some representative embodiments it has been discovered that zirconium oxide doped with gadolinium (Gd)-doped is more stable at higher temperatures. Therefore, doping zirconium oxide with gadolinium can significantly reduce the aforementioned structural changes in some cases, and in other cases may improve the durability properties of the coating, better than both undoped zirconium oxide and zirconium oxide doped with other materials.

Note from the foregoing that, in some exemplary embodiments, gadolinium-doped zirconium oxide and/or gadolinium oxide (e.g., Gd2O3 or other appropriate amount), the high-temperature phase of zirconium oxide, may be stabilized. In some cases, when gadolinium (Gd) doped zirconium oxide is used as a topcoat in paint, especially in low-E coating, the Gd doped ZrOx layer and the overall coating have better durability and thermal stability at higher temperatures. Furthermore, in some exemplary embodiments, the layer based on zirconium oxide doped with gadolinium (Gd) is subjected to lower stress than undoped zirconium oxide and/or zirconium oxide doped with other materials.

In some exemplary embodiments, despite the foregoing advantages of a zirconium oxide-based layer doped with gadolinium (Gd), the coating performance is improved without adverse side effects on the optical properties of low-E stacks. In some exemplary embodiments, the amount of gadolinium in the zirconium oxide-based layer can range From about 1 to 20% by weight, more preferably from about 5 to 17% (wt%), and most preferably from about 5 to 15% (wt%).

A metal target for layer deposition based on zirconium oxide doped with gadolinium (Gd)-doped is used, in some representative embodiments. In these embodiments, a target comprising zirconium and gadolinium may be used. In some representative embodiments, the target used to deposit the Gd-containing ZrOx layer can include a mixed system of ZrOxGdOx. The target by weight could include anywhere from about 1 to 40% gadolinium, more preferably about 5 to 30% gadolinium, and most preferably about 5 to 15% gadolinium.

In representative embodiments where the layer is deposited based on gadolinium (Gd)-doped zirconium oxide, with a metal target, the layer may be deposited in the presence of oxygen. The amount of oxygen can be measured based on the power of the Zr target, for example, in ml O2 per kilowatt of Zr target power. In some representative embodiments, oxygen is present in an amount from about 0.5 to 10 mL/kW, more preferably about 1 to 6 mL/KW, and most preferably about 2 to 4.2 mL/KW. Of course, the use of other environments can be realized in different models. These environments can include noble gases such as Ar, etc., or mixtures of reactive and inert gases (e.g., O2 and Ar).

In other representative embodiments, a ceramic target may be used. The deposition of the layer, which is based on zirconium oxide doped with gadolinium (Gd), can be done at room temperature in some cases and/or can be done at elevated temperatures. In other embodiments, gadolinium and zirconium may be precipitated in the presence of nitrogen (e.g., N2). After deposition, and after heating, the said nitride layer can become oxygenated, and can give rise to a zirconium oxide-based layer doped with gadolinium (Gd), in some cases.

A layer based on gadolinium (Gd)-doped zirconium oxide may be used as a topcoat in some representative embodiments. For example, a zirconium oxide based layer doped with gadolinium (Gd), according to some representative embodiments of the invention, may be used as a topcoat in a low-E coating. A “low-E coating” is a coating that has low emissivity and may include an infrared (IR) reflecting layer. The infrared (IR) reflective layer may include silver, but may also include other or substitute materials in some other embodiments. Other materials used for the IR reflective layer can be gold, nickel and/or nickel chromium, nickel chromium and alloys thereof, etc.

Figures 3-6 show some examples of layer stacks including a ZrOx layer including Gd according to some representative embodiments of the present invention. Of course, other layer stacks can be used in combination with other representations. The layer, which is based on zirconium oxide doped with gadolinium (Gd), may be used in coatings other than low-E coatings, and may also be located in the center of the stack and/or close to the glass substrate, in other representative embodiments. Furthermore, in other embodiments, more than one layer based on zirconium oxide doped with gadolinium (Gd) can be provided in a coating.

Figure 3 is a cross-sectional view of a coated product according to a representative embodiment of the invention. The coated product includes substrate 1 (e.g., clear, green, bronze, or blue-green glass substrate of about 1-12 mm, more preferably 1-10 mm, most preferably 3-9 mm), and a coating ( Or a layer system (30) provided on substrate 1 either directly or indirectly. The coating (or layer system) 30 includes: optional insulating layers 3 and/or 5, an optional first bottom contact layer 7 (contacting the infrared (IR) reflecting layer 9), a first conductive layer, preferably metallic, IR reflective ( IR) 9, an optional first top contact layer 11 (contact layer 9), insulating layer(s) 13 and/or 15, and a gadolinium (Gd)-doped zirconium oxide based layer 25, which may or may not be used as a topcoat and/ Or a coating coating 30 in some representative embodiments of the invention.

Still describing Figure 3, the optional dielectric layer 3 may be of or include a material such as a metal oxide such as tin oxide (which may be deposited in one or more steps in various embodiments of the invention). The optional dielectric layer 5 may be of or including a material such as silicon, partially or fully oxidized and/or nitrided in various embodiments of the present invention (e.g., Si3N4 or other suitable stoichiometric quantity). In some representative embodiments, the dielectric layers 3 and/or 5 can have a thickness of from about 20 to 60 nm, more preferably about 25 to 50 nm, more preferably from about 30 to 45 nm, the representative unconfined thickness being About 38 nm.

The infrared reflective layer (IR) reflecting 9 may be of or including silver and/or gold, etc. in some representative embodiments. However, the invention is not limited thereto, and in other representative embodiments the infrared reflective layer 9 can be made of or includes a material other than silver (e.g., nickel chromium, nickel chromium, nickel, and/or nickel alloy). In some representative embodiments, the thickness of the infrared reflective layer 9 can range from about 4 to 12 nm, more preferably from about 4 to 10 nm, most preferably from about 5 to 8 nm, and the representative unconfined thickness is about 6.7. Nanometer.

The optional first bottom contact layer 7 and the first top contact layer 11 may be of or including nickel chromium, zinc oxide and/or the like. In some representative embodiments, layer 7 and 9 can each have a thickness of less than about 2 nm, more preferably less than about 1.5 nm, and more preferably less than about 1.2 nm. The representative unconfined thickness of layer 7 can be about 1.1 nm, and the representative unconfined thickness of layer 9 can be about 0.8 nm. In other embodiments, layer 7 can have a thickness slightly greater than layer 9. However, in other embodiments, the thickness of layers 7 and 9 can be the same, and/or the thickness of layer 9 can be thicker than layer 7.

The optional dielectric layer 13 may be of or include a material such as silicon that has been partially or fully oxidized and/or nitrided (e.g., Si3N4 or other appropriate stoichiometry). The optional dielectric layer 15 may be of or include a material such as a metal oxide such as tin oxide (which may be deposited in one or more steps in various embodiments of the invention). In some representative embodiments, the thickness of the layers 13 and/or 15 can be from about 20 to 50 nm, more preferably from about 25 to 45 nm, and most preferably from about 280 to 380 nm, with a representative unrestrained thickness of 33 nm.

The gadolinium (Gd)-doped zirconium oxide-based layer 25 can be the overcoating (e.g., outer layer) of coating 30 in some representative embodiments. In some exemplary embodiments, the use of a topcoat of or including zirconium oxide doped with gadolinium (Gd) can result in a more durable and more thermally stable coating, with favorable optical properties. The expression zirconium oxide “doped with gadolinium (Gd)” as used herein means zirconium oxide, in any appropriate stoichiometric quantity, doped with gadolinium and/or gadolinium oxide (such as Gd2O3 or another appropriate stoichiometric quantity).

In some representative embodiments, only one of the insulating layers 3, 5, 13, 15 may be present in the coating. In some representative embodiments, more than one insulating layer 3, 5, 13, 15 may be present in the coating. Furthermore, one or none of the contact layers may be used in some representative embodiments. In other exemplary embodiments, such as those in which the infrared reflective layer includes a material other than silver, a higher barrier (e.g., away from the glass substrate) may be used. Instead of the top contact layer.

Figure 4 is a cross-sectional view of a coated product according to another representative embodiment of the present invention. The coating system and/or layer 40 of Figure 4 is similar to the coating and/or layer system 30 of Figure 3, except that the infrared (IR) reflective layer 9 of Figure 4 is based on a material other than silver. For example, the infrared (IR) reflective layer 9 may be of, or include, nickel chromium, nickel chromium, nickel and/or nickel alloy, or other suitable infrared (IR) reflective material. Preferably, layer 9 is conductive although it need not be conductive in all embodiments. Furthermore, Figure 4 illustrates that when the infrared (IR) reflective layer is based on a material other than silver, one or both of the upper and lower contact layers 7 and 9 may not be provided in those representative cases. In other representative embodiments, an optional barrier layer 14 may be provided on and in contact with the infrared (IR) reflective layer 9 as an alternative to or in addition to the contact layers.

Figure 5 is a cross-sectional view of a coated product according to another representative embodiment of the invention. The coating and/or layer system 50 of Figure 5 is similar to the coating and/or layer system 30 of Figure 3, except that the coating has two IR reflective layers. Therefore, in addition to the layers in the embodiment of Figure 3, the coated product may also include a second bottom contact layer 17 (contacting the infrared (IR) reflective layer 19), a second conductive infrared (IR) reflective layer 19, preferably metallic, A second upper contact layer 21 (which contacts layer 19), an insulating layer 23, and finally a protective insulating layer 25. Each “contact” layer 7, 11, 17, 21 touches at least one infrared (IR) reflecting layer (e.g. Ag, Au, etc.). The previously mentioned layers 3 - 25 constitute another representative example of low-E coating 30 applied to a glass or plastic substrate 1.

The optional second bottom contact layer 17 may be of or include nickel chromium, nickel chromium oxide, zinc oxide, and/or etc. The optional second top contact layer 21 may be of or include nickel chromium, oxide zinc and/or etc. The optional dielectric layer 23 may be of or include a material such as silicon that has been partially or fully oxidized and/or nitrided (e.g., Si3N4 or other appropriate stoichiometry) or a material such as a metal oxide such as tin oxide. tin oxide (which may be deposited over one or more steps in various embodiments of the invention). In some representative embodiments, layer 23 can include more than one insulating layer. In some representative embodiments, not all of the insulating layers 3, 5, 13, 15 and 23 may be present in the coating. In other representative embodiments, insulating layers 3, 5, 13, 15 and 23 may all be present in the coating. Furthermore, one or none of the contact layers may be used in some representative embodiments.

Figure 6 is an illustration of a representative embodiment of the invention. In the coating and/or layer system 60 shown in Figure 6, there is only one infrared (IR) reflecting layer 9, and the layer 9 is of or includes silver. Both the first lower contact layer 7 and the first upper contact layer 11 are of or include nickel chromium. There are insulating layers 3 and 13, which are made of or include silicon nitride. The topcoat 25 is the outer layer of the coating and includes zirconium oxide doped with gadolinium (Gd)-doped.

The preceding models are examples only, and not all layers described in each model should be included in the entire coating. Furthermore, in other representational models, additional layers may be used. Although several representative embodiments have been described in connection with low-E coatings, the invention is not limited to them. In other exemplary embodiments, zirconium oxide doped with gadolinium (Gd), may be used as a topcoat over any functional coating. In other exemplary embodiments, zirconium oxide doped with gadolinium (Gd), may be used as a layer in a coating, for example, the layer may be in the middle and contact at least two other layers. The zirconium oxide shall not be doped with gadolinium (Gd), topcoat and/or coating in all representative embodiments.

In some exemplary embodiments, in particular (but not limited to) when a layer based on zirconium oxide doped with gadolinium (Gd) is used as a topcoat (e.g., outer layer) in a low-E coating, the layer thickness can range 25 From about 1 to 15 nm, more preferably from 2.5 to 10 nm, and most preferably from about 3 to 7 nm, with a representative thickness of 5 nm.

The coating system 30 and/or layer 25 can be insulating in some representative embodiments.

Other layer(s) may also be provided below, within, or on top of the coating shown 30. Therefore, while the layer or coating system is “on” or “supported by” substrate 1 (directly or indirectly), it may also be provided With another layer(s) in between.

Thus, for example, the coating 30 of Figure 3 and its layers may be deemed to be “on” or “supported by” substrate 1 even if another layer(s) are provided between layer 3 and substrate 1. Furthermore, some of the layers of the coating shown may be removed In some embodiments, and in other embodiments, other layers are added to the present invention without deviating from the overall scope of some embodiments of the present invention. In some representative embodiments, the coating 30 can consist primarily of layers 3, 7, 9, 11, 13, 25, and layer 25 can be exposed to the atmosphere (e.g., layer 25 can be the outer layer of the coating in some representative embodiments ). The ZrOx inclusion (Gd) overcoatings described herein may be used in combination with low-E coatings, such as those described in US Patent Applications No. 2009/0214480; 2009/0205956; 2009/0324934, 2009/0324967, 2010/0075155, and 2010/0104840, along with U.S. Patent Applications Serial No. 12/453,125; And 12/453,836 12/662,561 and 12/662,562, the entire contents of which are included by reference in this application.

A coated product as described herein (e.g., see Figures 3-6) may be treated with or without heat (e.g., heat hardening) in some exemplary embodiments.

The expressions “heat treatment” and “heat treatment” as used herein mean heating the body to a temperature sufficient to achieve thermal strengthening and/or thermal strengthening of the body containing the glass.

The definition includes, for example, heating a coated product in an oven or stove at a temperature of at least about 550°C, more preferably at least about 580°C, more preferably at least about 600°C, and more preferably at least about 620°C. Lowest, most preferably around 650°C at least for a period sufficient to allow heat strengthening and/or strengthening.

This may be done for a period of at least about 2 minutes, or up to about 10 minutes, in some representative embodiments.

Some or all of the layers described herein may be deposited, directly or indirectly, on substrate 1 by sputtering or other suitable chip formation technique such as combustion vapor deposition, combustion deposition, etc.

While the invention has been described in association with what is for the time being considered the most and best practical embodiment, it is understood that the invention is not limited to the disclosed embodiment, but, on the contrary, is intended to cover various modifications and equivalent equipment included within the scope and content of the claims. the attached.