ITCO20090038A1 - PROCESSES TO REDUCE A SURFACE BEFORE NON-ELECTRIC PLATING - Google Patents

Description

DESCRIPTION

NOTE ART

The present disclosure relates to processes for roughening a surface prior to non-electric nickel plating.

The steel components of industrial and marine turbojet engines are subjected, during normal use, to various operating conditions, in particular as regards the ambient atmosphere. For this reason, the steel substrates are often coated with a layer resistant to erosion and corrosion.

To improve the adhesion of the layer resistant to erosion and corrosion, it is generally known that the roughness of a surface can be an important constituent element in a binder or coating creation operation. The roughness, or roughness, of the surface provides a "mechanical key" to the coating material or adhesive used in binder creation to assist in bonding the coating material or bonding layer to the parent material and to ensure the structural integrity of the finished component.

The conventional methods of surface preparation used in heavy industry, such as the construction of turbojet engines, substantially include mechanical processes, such as shot blasting, micro-finishing, grinding and the like. Each of these methods involves contacting the surface with an abrasive medium; typically, these methods are not easily controlled to obtain a very accurate surface preparation and are not usually used when you want to obtain a particular pattern for forming a mechanical key. Conventional methods of surface preparation can also introduce deformations or other undesirable damage to the surface or substrate; the abrasive material can creep into some mother material or otherwise leave behind some contaminating particles or residues that will require a further process to clean the surface and remove any contaminant or residue. In addition to this, some surfaces, such as those found in the rotors of gas compressors, are coated with nickel to ensure resistance to corrosion and erosion. Obtaining adherence to the coating layer can be difficult, especially in hard-to-reach internal cavities that are not accessible with visual methods such as shot blasting. As a result, there remains a need for improved methods for roughening a surface, particularly with regard to non-visual surfaces that are often found on complex geometry parts.

SUMMARY DESCRIPTION

Processes that usually include roughening of a surface on a base metal substrate are disclosed herein. In one embodiment, a process for roughening a base metal surface involves contacting the surface with aqueous solution containing oxalic acid, sulfuric acid, and hydrogen peroxide at an effective temperature and period of time to roughen an average roughness surface greater than 60. Ra.

In another embodiment, a process for making a turbine component comprising the supply of an unfinished turbine component; immersion of the component in an aqueous solution substantially composed of oxalic acid, sulfuric acid and hydrogen peroxide to roughen a surface of the component to an average roughness greater than 60 Ra; and depositing at least one layer of erosion and corrosion resistant material on the surface.

In yet another embodiment, a process for plating a substrate which has at least one non-visual surface including etching the substrate which has at least one non-visual surface with aqueous solution containing oxalic acid, sulfuric acid and hydrogen peroxide for a period of time effective for providing surface roughness greater than 60 Ra; and a non-electrical metal plating on the substrate having at least one non-visual surface.

The disclosure can be understood more quickly by referring to the following detailed description of the various features of the disclosure and the examples set forth therein.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the figures in which the same elements are numbered in the same way:

Figure 1 illustrates scanning electron microscope images of a base metal substrate surface after contact with oxalic acid and sulfuric acid solution for a period of 5 minutes at various temperatures; And

Figure 2 illustrates scanning electron microscope images of a base metal substrate surface after contact with oxalic acid and sulfuric acid solution for a period of 10 minutes at various temperatures; And

DETAILED DESCRIPTION

The present disclosure is generally directed to a process of roughening a base metal substrate surface prior to non-electric plating. For example, the process can be practiced on base metal substrates consisting of carbon steel and low alloy steel. Advantageously, the process is effective for roughening substrates formed from the materials indicated above and which have non-visual surfaces, thereby increasing the surface and improving the adhesion of coating layers resistant to erosion and corrosion with non-electric plating. Among the relevant examples of suitable substrates having non-visual surfaces we can include, without limitation, compression rotors, impellers and the like, of turbojet engines.

The process generally includes contacting the base metal substrate with a roughening chemical solution. Contact is not intended to be limited to a particular method and may include immersion, nebulization and the like. In one embodiment, the roughening chemical solution generally includes an acid with the optional addition of non-foaming agents, thickeners and wetting agents. A wetting agent is a substance, usually a surfactant, capable of reducing surface tension.

In one embodiment, the chemical roughening solution contains oxalic acid, sulfuric acid, hydrogen peroxide and water, with the optional addition of non-foaming agents, thickeners and wetting agents. A wetting agent is a substance, usually a surfactant, capable of reducing surface tension. In one embodiment, the chemical roughening solution contains, in percent by weight, about 0.5 to 5% oxalic acid, about 0.01% to about 0.5% sulfuric acid (98% w / w), from about 0.1 to 5% of hydrogen peroxide (35% w / w), with water as the residue and any optional additives. In one embodiment, the chemical roughening solution contains, in percent by weight, about 0.5 to 4% oxalic acid, about 0.05% to about 0.3% sulfuric acid (98% w / w), about 0.1 to 3% of hydrogen peroxide (35% w / w), with water as the residue and any optional additives. In yet another embodiment, the chemical roughening solution contains, in percentage by weight, from about 2.5 to 3.5% of oxalic acid, from 0.5% to about 0.15% of sulfuric acid (98% w / w), from about 0.8 to 2% of hydrogen peroxide (35% w / w), with water as the residue and any optional additives. A preferential solution contains about 3% oxalic acid, about 0.15% sulfuric acid by weight (98% w / w), 1.5% hydrogen peroxide (35% w / w) with water as remaining. While oxalic acid and sulfuric acid have been used alone and separately in combination with other acids and solvents for similar purposes, the proposed combination provides maximum surface roughening, i.e. it roughens evenly over the entire surface without damaging the substrate. In addition, a minimal amount of blind holes or deep cracks no larger than 10 microns are formed. Cracks no wider than 10 microns are susceptible to the formation of hydrogen bubbles during exposure of the substrate to a subsequent non-electric plating process. The process is in itself respectful of the environment, valid and effective for roughening surfaces greater than 60 Ra. An added benefit is that it only removes a modest amount of base metal.

In some embodiments, the process of this disclosure is carried out at temperatures ranging from room temperature to about 50 ° C; at temperatures from about 20 ° C to 40 ° C in other embodiments and at temperatures from about 20 ° C to 30 ° C in still other embodiments. The base metal substrate comes into contact with the solution of oxalic acid, sulfuric acid and hydrogen peroxide at the temperature indicated above and for a period of time effective to roughen the surface. Generally speaking, the time period is less than 60 minutes for most builds, less than 30 minutes for other builds, and less than 10 minutes for yet other builds. In one embodiment, the base metal substrate is exposed to the oxalic acid and sulfuric acid solution at a temperature of 30 ° C for a period of 10 minutes. In one embodiment, the chemical roughening solution contains, in percent by weight, about 0.5 to 5% oxalic acid, about 0.01% to about 0.5% sulfuric acid (98% w / w), about 0.1 to 5% of hydrogen peroxide (35% w / w), with remaining water and any optional additives.

After roughening, the surface can be coated with a coating layer. For example, a material resistant to erosion and corrosion such as a nickel alloy material can be deposited on the roughened surface.

Optionally, the base metal substrate is cleaned with a solvent before being treated with the roughening solution. Among the suitable solvents we can include, but not strictly limitative, hydrocarbons (for example pentane or hexane); halocarbons; ethers (eg ethyl ether (Et2O), tetrahydrofuran ("THF"), ethylene glycol monomethyl ether or 2-methoxy ethyl ether (diglyme); nitriles (eg CH3CN); aromatic compounds (eg benzotrifluoride), alcohols and water. Other exemplary solvents we can include lactates, pyruvates and diols. Among these solvents we can include, but not strictly limiting, acetone, 1,4-dioxane, 1,3-dioxolane, ethyl acetate, cyclohexanone, acetone, 1-methyl-2-pyrodidianone (NMP ) and methyl ethyl ketone. Other solvents include dimethylformamide, dimethylacetamide, N-methyl pyrrolidone, ethylene carbonate, propylene carbonate, glycerol and derivatives, naphthalene and substitute versions, acetive acid anhydride, propionic acid and propionic acid anhydride, dimethyl sulphone, benzophenone, diphenyl sulphone, phenol, m-cresol, dimethyl sulfoxide, diphenyl ether, terphenyl and the like. Among the other solvents we can include propylene glycol propyl ether (PGPE), methanol, ethane lo, 3-heptanol, 2-methyl-1-pentanol, 5-methyl-2-hexanol, 3-hexanol, 2-heptane, 2-hexanol, 2, 3-dimethyl-3-pentanol, propylene glycol methyl ether acetate ( PGMEA), ethylene glycol, isopropyl alcohol (IPA), n-butyl ether, propylene glycol n-butyl ether (PGBE), 1-butoxy-2-propanol, 2-methyl-3-pentanol, 2-methoxyethyl acetate, 2- butoxyethanol, 2-ethoxyethyl acetoacetate, 1-pentanol and propylene glycol methyl ether.

Cleaning can also include high-energy agitation of the cleaning agent with the base metal substrate, for example sonification. Once cleaned, the chemically roughened substrate is coated non-electrically with a metallic coating, such as nickel. The particular non-electrical coating process is not intended to be limited. US patents no. [] disclose exemplary non-electrical coating processes. Metallographic results were obtained which show excellent bonding between the coating and the roughened surface.

In all examples, the chemical roughening treatment generates a pickling residue or impurity following incomplete dissolution. These pickling impurities are conveniently removed by ultrasonic cleaning with a suitable cleaning agent.

The examples below are presented for illustrative purposes only and are not intended to limit the scope of the invention.

Example 1.

In this example, alloy A182F22, the substrates were treated with oxalic acid and sulfuric acid solution and the surface roughness was analyzed. The oxalic acid, sulfuric acid and hydrogen peroxide solution was composed as follows: oxalic acid at 31.25 g / L, sulfuric acid (98% w / w) at 1.25 mL / L and hydrogen peroxide (35% w / w) to 16 mL / L. The temperature and the time period were varied. The results are reported in Table 1 and contrasted with the controls in which the surface was not attacked and with a substrate containing pickling impurities. The surface roughness was measured with the Mitutoyo SJ400 surface analyzer.

Table 1.

Etching agent Temp. Time Ra Ra (<o> C) (minutes) (microns, (mean deviation) standard) Sulfuric hydrogen peroxide 20 5 91 10 oxalic

Sulfuric hydrogen peroxide 20 10 79 24 oxalic

Sulfuric hydrogen peroxide 30 5 114 15 oxalic

Sulfuric hydrogen peroxide 30 10 183 25 oxalic

Sulfuric hydrogen peroxide 40 5 86 13 oxalic

Sulfuric hydrogen peroxide 40 10 105 20 oxalic

Agent-free control --- --- 43 3 of attack

Control containing --- --- 74 11 pickling impurities

The results show high surface roughness. In each example, the

surface roughness (Ra) was greater than 60. Figures 1 and 2

show scanning electron microscope images taken at

different temperatures and in different times, which demonstrate the roughness

generated on the surface. The surface roughness is uniform and they are not

Neither blind holes nor cracks below 10 microns were observed.

In summary, the clauses listed below summarize the subject here

disclosed. Clause 1, a process for treating a surface of a

base metal substrate, said process comprising: contacting the

surface with aqueous solution containing oxalic acid, acid

sulfuric and hydrogen peroxide at a temperature and for a period of time effective to roughen a surface with an average roughness greater than 60 Ra. Clause 2, the process of Clause 1, where the base metal substrate is a turbine component that has at least one non-visual surface. Clause 3, the process of Clause 1, where the aqueous solution contains, in percentage by weight, about 0.01 to 0.5% oxalic acid, about 0.1% to 0.5% sulfuric acid (98 % w / w) and hydrogen peroxide (35% w / w), with water remaining. Clause 4, the process of Clause 1, further comprising a wetting agent, a thickening agent and a non-foaming agent. Clause 5, the process of Clause 1, where surface contact with the aqueous solution includes heating the solution to a temperature within a range of room temperature to 50 <o> C and for a period of time less than 60 minutes . Clause 6, the process of Clause 1, further comprising cleaning the surface prior to contact of the surface with the aqueous solution. Clause 7, the process of Clause 1, where the surface includes a non-visual surface. Clause 8, the process of Clause 1, where the base metal substrate includes carbon steel, alloy steel, stainless steel, nickel, cobalt or zirconium alloys.

Clause 9 relates to a process of making a turbine component, comprising: supplying an unfinished turbine component; immersion of the component in an aqueous solution composed of oxalic acid, sulfuric acid and hydrogen peroxide to roughen a surface of the component to an average roughness greater than 60 Ra; and depositing at least one layer of erosion and corrosion resistant material on the surface. Clause 10, the process of Clause 9, where the solution is at a temperature within a range of room temperature to 50 <o> C. Clause 11, the process of Clause 9, where the aqueous solution contains, in percentage by weight, about 0.01 to 0.5% oxalic acid, about 0.1% to 0.5% sulfuric acid (98 % w / w) and hydrogen peroxide (35% w / w), with water remaining. Clause 12, the process of Clause 9, further comprising a wetting agent, a thickening agent and a non-foaming agent. Clause 13, the process of Clause 9, further comprising cleaning the unfinished turbine component prior to surface contact with the aqueous solution. Clause 14, the process of Clause 13, where cleaning includes exposure of the turbine component to a solvent. Clause 15, the process of Clause 9, where the component includes non-visual surfaces. Clause 16, the process of Clause 9, where the immersion of the component in an aqueous solution roughens the temperature to an entity greater than 60 Ra. Clause 17, the process of Clause 9, where the base metal substrate includes carbon steel, alloy steel, stainless steel, nickel, cobalt or zirconium alloys. Clause 18 refers to a process of plating a substrate that has at least one non-visual surface, said process comprising: etching the substrate that has at least one non-visual surface with an aqueous solution composed of oxalic acid, sulfuric acid and water oxygenated for an effective period of time to provide surface roughness greater than 60 Ra; and non-electrical plating of a metal on top of the substrate having at least one non-visual surface. Clause 19, the process of Clause 18, where the metal is nickel and where the base metal substrate includes carbon steel, alloy steel, stainless steel, nickel, cobalt or zirconium alloys. And finally Clause 20, the process of Clause 18, where the aqueous solution contains, in percentage by weight, from about 0.01 to 0.5% of oxalic acid, from 0.1% to about 0.5% of acid sulfuric (98% w / w) and hydrogen peroxide (35% w / w), with water remaining.

Note that the terms "first / a", "second / a" and the like used here are not intended to denote order, quantity or importance, but rather to distinguish one element from another. The terms "one", "one", "one" are not intended to denote a limitation of quantity, but rather to denote the presence of at least one of the elements indicated. The adverb "about" used in relation to a quantity includes the indicated value and has the meaning suggested by the context (for example, it includes the degree of error associated with the measurement of the specific quantity). Note that all ranges indicated in these specifications are inclusive and can be combined independently. All quantities, parts, ratios and percentages used herein are by weight, unless otherwise stated.

While the invention has been described with reference to its embodiments, those skilled in the art will understand that various changes can nevertheless be made and that some elements of the invention can be replaced with equivalent elements without thereby deviating from the scope of the invention. of the invention. In addition to this, many changes can be made to adapt a particular situation or a particular material to the teachings of the invention, without thereby deviating from what is the main scope of the invention. Therefore, it is understood that the invention is not limited to the particular embodiments disclosed as an optimal mode contemplated for applying the present invention, but that the invention includes all the embodiments that fall within the scope of the claims appended hereto.

Claims (10)

CLAIMS 1. A process for treating a surface of a base metal substrate, said process comprising: contact of the surface with aqueous solution containing oxalic acid, sulfuric acid and hydrogen peroxide at a temperature and for a period of time effective to roughen a surface of average roughness greater than 60 Ra. 2. The process of Claim 1, where the base metal substrate is a turbine component which has at least one non-visual surface. The process of any one of the preceding claims, wherein the aqueous solution contains, in percentage by weight, from about 0.01 to 0.5% of oxalic acid, from 0.1% to about 0.5% of sulfuric acid (98% w / w) and hydrogen peroxide (35% w / w), with water remaining. The process of any one of the preceding claims, further comprising a wetting agent, a thickening agent and a non-foaming agent. The process of any one of the preceding claims, where the contact of the surface with the aqueous solution comprises heating the solution to a temperature within a range of room temperature to 50 <o> C and for a period of time less than 60 minutes. 6. The process of Claim 1, where the base metal substrate comprises carbon steel, alloy steel, stainless steel, nickel, cobalt or zirconium alloys. The process of any one of the preceding claims, further comprising cleaning the surface prior to contacting the surface with the aqueous solution. 8. The process of Claim 7, where cleaning includes the exposure of the turbine component to a solvent. The process of any one of the preceding claims, further comprising the non-electric plating of a metal on a substrate having at least one non-visual surface subsequent to the contact of the surface with the aqueous solution. 10. The process of Claim 9, the process of Clause 18, where the metal is nickel and where the base metal substrate comprises carbon steel, alloy steel, stainless steel, nickel, cobalt or zirconium alloys. CLAIMS / CLAIMS 1. A process for treating a surface of a base metal substrate, the process comprising: contacting the surface with an aqueous solution comprising oxalic acid, sulfuric acid, and hydrogen peroxide at a temperature and for a period of time effective to roughen the surface to an average roughness greater than 60 Ra. 2. The process of Claim 1, wherein the base metal substrate is a turbine component having at least one non-line of sight surface. 3. The process of any one of the preceding claims, wherein the aqueous solution comprises, by weight percent, about 0.01 to about 0.5% of the oxalic acid, about 0.1% to about 0.5% of the sulfuric acid (98% w / w ) and of the hydrogen peroxide (35% w / w), with the balance being water. 4. The process of any one of the preceding claims, further comprising a wetting agent, a thickener, or a non-foaming agent. 5. The process of any one of the preceding claims, wherein contacting the surface with the aqueous solution comprises heating the aqueous solution to a temperature within a range from room temperature to 50 ° C and for a period of time less than 60 minutes. 6. The process of Claim 1, wherein the base metal substrate comprises carbon steel, alloy steel, stainless steel, nickel-based, cobaltbased, or zirconium-based alloys. 7. The process of any one of the preceding claims, further comprising cleaning the surface prior to contacting the surface with the aqueous solution. 8. The process of Claim 7, wherein cleaning comprises exposing the turbine component to a solvent. 9. The process of any one of the preceding claims, further comprising electroless plating a metal onto the substrate having at least one non-line of sight surface subsequent to contacting the surface with the aqueous solution. 10. The process of Claim 9, wherein the metal is nickel, and wherein the base metal substrate comprises carbon steel, alloy steel, stainless steel, nickel-based, cobalt-based, or zirconium-based alloys.