Methods of inhibiting oxidation during diffusion boriding

Abstract

Methods and assemblies for diffusion-based boriding as provided. The methods include accounting for faster immersion of a sample by applying an additional power to heat the electrolyte prior to immersion and applying a negative bias voltage to the sample to mitigation or eliminate oxidation. A fixture including a sample holder to apply the negative bias voltage is also provided.

Description

METHODS OF INHIBITING OXIDATION DURING DIFFUSION BORIDINGTECHNICAL FIELD

[0001] This disclosure relates to methods and systems for diffusion bonding that eliminate or mitigate an oxide barrier layer which hinders diffusion of boron.BACKGROUND

[0002] Bonding surface regions such as to provide borides of transition metals may provide many favorable properties. For example, titanium diboride (TiB2) surface regions may be beneficial due to the unique properties of this material such as excellent wear resistance and hardness. Steels or steel alloys such as high-speed steels (HSSs) are commonly used in tooling (e.g., drills, taps, reamers, cutters, hole machining, and saws). These steels may have good mechanical, chemical, and thermal properties but suffer from poor wear resistance reducing their performance and lifespan. Accordingly, technologies that improve wear resistance of tooling materials such as steel are still needed. Diffusion-based boriding is becoming more popular, for example, U.S. Patent No. 10,287,700 discloses methods of forming a titanium diboride surface region and is hereby incorporated by reference in its entirety.

[0003] However, such technologies still suffer from challenges such as oxidation during the process. For example, during the boriding process, samples can be significantly oxidized while suspended above the high-temperature electrolyte before immersion. This may rapidly form an oxide layer on the samples which then acts as a barrier layer hindering the diffusion of the boron atoms into the surface region of the samples and reduces the efficiency of boriding. Mitigating or eliminating oxidation (e.g., an oxidation layer) may further improve boriding efficiency and the resulting properties.SUMMARY

[0004] A fixture for electrochemical boriding is provided. The fixture includes a bus bar, at least one arm e.g., two arms) cooperating with the bus bar, and a sample holder cooperating with the bus bar. The at least one arm is movable from a first position to a second position such that thefirst position provides a first contact area with a surface and the second position provides a second contact area with a surface that is greater than the first contact area. The sample holder is arranged such that a sample in the sample holder, when in the first position, is partially immersed in the electrolyte of an adjacent electrolysis cell and when in the second position the sample is more immersed e.g., fully immersed) in the electrolyte.

[0005] A bonding system is provided. The boriding system includes an electrochemical cell and fixture. The electrochemical cell includes a boron- containing electrolyte and an anode in contact with the electrolyte. A sample retained by a sample holder of the fixture may act as the cathode. The fixture is arranged on the electrochemical cell. The fixture is movable from a first position to a second position. In the second position, a sample retained by the sample holder is immersed in the electrolyte to a greater extent than the first position. The second position also provides a greater power to the cell than the first position.

[0006] A method of boriding is provided. The method includes heating a boron-containing electrolyte of an electrolysis cell and immersing an article into the electrolyte. Heating is provided by applying a first holding power to maintain the temperature of the electrolyte at a steady temperature and applying a second additional power based on the article and the article immersion rate. The article is immersed for a duration of time to provide a boride treatment on the article.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a schematic view of a first embodiment of a fixture in a first position.

[0008] FIG. 2 is a schematic view of the embodiment of the fixture in a second position.

[0009] FIG. 3 is a schematic view of the embodiment of the fixture in a third position.

[0010] FIG. 4 is a schematic view of a second embodiment of a fixture.

[0011] FIG. 5 is a schematic view of the second embodiment of the fixture in a second position.

[0012] FIG. 6 is a schematic view of the second embodiment of the fixture in a third position.

[0013] FIG. 7 is a schematic view of the second embodiment of the fixture in a fourth position.

[0014] FIG. 8 is a schematic view of an embodiment of an electrochemical diffusion-based boriding system with a containment structure.

[0015] FIG. 9 is a flowchart of a method of boriding an article.

[0016] FIG. 10 is a chart illustrating additional power to maintain an electrolyte temperature based on a duration of time for immersing a sample.DETAILED DESCRIPTION

[0017] Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale. Some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments of the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.

[0018] Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and / or use are to be understood as modified by the word about in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: percent, “parts of,” and ratio values are by weight. The term “polymer” includes “oligomer,” “copolymer,” “terpolymer,” and the like. The description of a group or class of materials as suitable or preferred for given purpose in connection with the invention implies the mixtures of any two or more of the members of the group or class are equally suitable or preferred. Molecular weights provided for any polymers refers to number average molecular weight. Description of constituents in chemical terms refers to the constituents at the time of addition toany combination specified in the description, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.

[0019] This invention is not limited to the specific embodiments and methods described below, as specific components and / or conditions may vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present invention and is not intended to be limiting in any way.

[0020] As used in the specification and the appended claims, the singular form “a,” “an,” and “the” comprise plural referents unless the context clearly indicates otherwise. For example, reference to a component in the singular is intended to comprise a plurality of components.

[0021] The term “substantially,” “generally,” or “about” may be used herein to describe disclosed or claimed embodiments. The terms “substantially,” “generally,” or “about” may modify a value or relative characteristic disclosed or claimed in the present disclosure to signify within manufacturing tolerances and / or within ± 0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% or 10% of the value or relative characteristic.

[0022] With respect to the terms “comprising,” “consisting of,” and “consisting essentially of,” where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms.

[0023] It should also be appreciated that integer ranges explicitly include all intervening integers. For example, the integer range 1-10 explicitly includes 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Similarly, the range 1 to 100 includes 1, 2, 3, 4 . . . 97, 98, 99, 100. Similarly, when any range is called for, intervening numbers that are increments of the difference between the upper limit and the lower limit divided by 10 can be taken as alternative upper or lower limits. For example, if the range is 1.1. to 2.1 the following numbers 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 can be selected as lower or upper limits.

[0024] Referring to FIG. 1, a fixture 100 such as to provide negative bias voltage to an articlc / samplc 102 for boriding and / or prior to boriding is provided. In one or more embodiments, the fixture 100 provides electrical conductivity and / or immerses the article / s ample 102 into an electrochemical boriding cell. An example of an electrochemical boriding system is shown in FIGS. 2-8. Again, referring to FIG. 1, the fixture 100 may include at least one bus bar 104 cooperating with a sample holder 106. In one or more embodiments, the sample holder is capable of holding one or more samples (e.g., a plurality of samples or at least two samples). In a variation, the fixture 100 includes one or more e.g., a plurality of or at least two) movable arms 108, 110. In a refinement, the movable arms 108, 110 may pivotally cooperate with the bus bar 104 such as at joints 112, 114 (e.g., hinged arms). In various embodiments, the movable arms 108, 110 may also cooperate with one or more wheels 116 (e.g., a plurality of or at least one wheel each) to facilitate movement or translation of the aims 108, 110 such as along a surface 118.

[0025] In one or more embodiments, the fixture 100 cooperates with a machine (not shown) to facilitate movement such as a crane. For example, mobile rolling cable crane may be used. In a variation, the crane is electrically isolated and / or insulated such that it does not interfere with electrochemically boriding a sample 102 in the sample holder 106. In various embodiments, the machine / crane is fixed to the fixture such that it may operate to move the fixture to and from different positions (e.g., a position where the sample 102 is not immersed, a position where the sample 102 is partially immersed, and / or a position where the sample 102 is fully immersed). In a refinement, the fixture 100 and machine cooperate in a manner that allows the movable arms 108, 110 to move between a straightened high-power position and a bent low-power position.

[0026] In various embodiments, the one or more movable arms 108, 110 each have a first end and a second end with each joint respectively being disposed at a first end and one or more wheels 116 being respectively disposed at the second end. For example, each aim 108, 110 may include a wheel 116 disposed at a second (distal) end opposite a first end that is proximal the bus bar 104.

[0027] Thus, as the wheels 116 roll or translate along the surface 118 inward towards each other, the one or more joints 112, 114 may bend to lift the sample 102 / sample holder 106. Similarly, as the wheels 116 roll or translate along the surface 118 away from each other or outward, the joints 112, 114 straighten to lower the sample 102 / sample holder 106 such as into an electrochemicalbonding cell. It should be understood that in various embodiments, the fixture 100 by itself may not lift the sample 102 without the assistance or without cooperating with a machine such as a crane to facilitate lifting (and / or lowering). For example, the fixture 100 may cooperate with a cable crane such that as the cable is retracted by the crane the bus bar 104, sample holder 106, and a sample 102 disposed in the sample holder are lifted while the joints 112, 114 simultaneously function to bend such that the movable arms 108, 110 move inward towards each other and the wheels 116 translate inward towards each other along the surface 118. As the crane releases the cable it lowers the bus bar 104, sample holder 106, and sample 102 disposed therein. As bus bar 104, sample holder 106, and / or sample 102 are lowered the joints again simultaneously operate such that the wheels 116 translate outward along the surface 118 moving the moveable arms 108, 110 away from each other. Thus, in various embodiments, the inward-outward horizontal movement of the distal ends of the arms 108, 110 (along a first direction) correspond to vertical movement of the sample 102 / sample holder 106 (along a separate different direction).

[0028] In a variation, the surface 118 may be the surface of one or more additional bus bars. In a refinement, the bus bars are negatively polarized such that they may negatively polarize the sample 102 when in electrical communication. Accordingly, in one or more embodiments, the various components described herein such as the wheels 116 and arms 108, 110 are electrically conductive. Applying a small negative charge alters the surface electron charge potential of the sample 102 thereby decreasing the bonding affinity of the surface atoms of the sample 102 with oxygen atoms, which may reduce oxidation and prevent formation of an oxidiation barrier layer. In one or more embodiments, the fixture 100 may be used in an electrochemical bonding system.

[0029] In various embodiments, the fixture 100 may provide different areas of contact such as with or between the bus bar 104 and the surface 118 such that a greater contact area allows greater power and smaller contact areas allows less power to the electrochemical system. In one or more embodiments, the wheels 116 and the surface 118 form a first conductive (moving) contact area (e.g., surface area) at their interface such as when the joints 112, 114 are bent. For example, FIGS. 1-2, 4, and 6-8 demonstrate bent low-power positions where the sample 102 is not immersed or only partially immersed in an electrolyte. In the high-power straight position, a surface of the arms 108, 110 and / or bus bar 104 form a second conductive contact area e.g., surface area) at the interface between them. For example, FIGS. 3 and 9 demonstrate a straight high-power positionwhere the sample 102 is fully immersed in the electrolyte. In a refinement, the power provided from the second contact area or position is greater than the power provided from the first position such that power may be regulated by the position of the fixture 100. In a variation, this may be a result of the size of the contact area. For example, the contact area of the second position may be greater than the contact area of the first position. In various embodiments, low power may refer to power sufficient to prevent / mitigate oxidation but insufficient to carry-out active boriding. In one or more embodiments, high-power may refer to power sufficient to carry out active boriding.

[0030] Referring to FIG. 2, electrochemical boriding system 200 having a fixture 202 is shown. The electrochemical boriding system 200 also includes an electrolytic electrochemical cell 204 cooperating with the fixture 202. For example, the electrochemical cell 204 is disposed beneath the fixture 202 such that in the bent position a sample 210 held by the sample holder 208 is not immersed or only partially immersed in an electrolyte 212 of the electrochemical cell 204 and in the straight position the sample 210 is fully immersed in the electrolyte 212. It should be understood that the sample 210 may not need to be fully immersed but rather the surface region being borided must be immersed, however, there may be undesirable effects boriding with only partial immersion Accordingly, in one or more embodiments, it may be preferably that in the high- power position the sample 210 is fully immersed. Boriding occurs during electrolysis of the electrochemical cell 204. In one or more embodiments, the fixture 202 includes one or more bus bar(s) 206 and a sample holder 208 to hold a sample 210. In a refinement, the sample holder 208 cooperates with at least one of the bus bars 206 by being in electrical communication therewith. In various embodiments, the electrolytic electrochemical cell 204 includes an electrolyte 212 containing boron (i.e., boron-containing electrolyte). In a refinement, the electrolyte 212 is a molten salt electrolyte. For example, the electrolyte 212 may include sodium tetraborate such as at 90% by weight. In one or more embodiments, electrolysis may induce diffusion-based boriding.

[0031] During active boriding, electrolysis may break down the boron species present in the electrolyte. For example, the molten sodium tetraborate (e.g., NaiEFO?) may provide free boron which may diffuse into the surface region of the sample 210 and bind with the metal surface molecules such as titanium.

[0032] In various embodiments, applying a minimum power / current / voltage prior to or during immersion of the sample prevents or mitigates oxidation. In various embodiments, this may be referred to as impressed current cathodic protection and induces a potential difference between the cathodic sample and the anode. The potential difference is large enough to prevent oxidation reactions. For example, a controlled electrical current may be applied to the cathode and / or sample. In various embodiments, the minimal current required to protect the cathode / sample may be determined using Faraday’s law:where I is the current required to provide cathodic protection, W is the weight loss due to oxidation, D is the density of the metal substrate, n is the valence of the metal ion being reduced, F is Faraday’s constant (e.g., 96.485 C / mol), and Z is the number of electrons involved in the reduction reaction. In one or more embodiments, this may be applied as a current density by considering the surface area of the sample 210 (and sample holder 208).

[0033] In various embodiments, the high-power or flat position, for example, shown in FIGS. 3 and 7 may provide power suitable for electrolysis or active boriding. In one or more embodiments, impressed current cathodic protection may be applied during the remaining stages / positions to protect the sample from oxidation. In various embodiments, the electrochemical cell 204 maintains a constant current density of, for example, 200 mA / cm2during the active boriding stage. In one or more embodiments, the electrochemical boriding system 200 may include a heater 214 such as a furnace. In a variation, the fixture 202 and the electrochemical cell 204 may be in the heater 214. In a refinement, the heater 214 is an induction furnace. For example, a medium frequency (e.g., 200 to 2,500 Hz) induction furnace may be used. In various embodiments, the heater 214 may heat the electrolyte 212 to a molten state. For example, the heater 214 may heat the electrolyte from 900 to 1000°C (e.g., to 950°C) for 15 to 60 minutes.

[0034] In one or more embodiments, the fixture 202 may move from a first position (as shown in FIG. 1) to a second position (as shown in FIG. 2), and / or even a third position (as shown in FIG. 3). In a variation, the first position may provide less power than the second position which may provide less power than the third position. In a refinement, the first position may provide no power, the second position may provide a power sufficient to prevent oxidation but not active boriding,and the third position may provide a power sufficient for active bonding. In the first position, the sample holder 208 may hold a sample 210 a distance away from of the electrolyte 212. In the second position, the sample holder 208 may partially immerse the sample 210 in the electrolyte 212. In the third position, the sample holder 208 may further immerse the sample 210 in the electrolyte 212 such as by fully immersing the sample 210 into the electrolyte 212. In one or more embodiments, the fixture 202 provides an inactive position as in FIG. 1, a low-power position as in FIG. 2, and a high-power position as is FIG. 3.

[0035] In various embodiments, the electrochemical cell 204 may include a plurality of electrodes (e.g., a pair including an anode and a cathode) each in contact with the electrolyte 212 and a power source (not shown). In a refinement, the anode may be high-silicone graphite. In a variation, the sample 210 may act as an electrode (e.g., cathode). The sample may be negatively polarized. Altering the surface charge potential may cathodically protect the sample 210 such as from oxidation. In one or more embodiments, this is achieved by applying a low electric current through the sample. In various embodiments, the sample 210 may be negatively charged before the boriding process to prevent oxidation. When the sample acts as the cathode immersing the sample into the electrolyte closes the electrical circuit thus permitting electrical conductivity and removing the sample from the electrolyte breaks or opens the electrochemical circuit. In one or more embodiments, the electrolyte 212 is disposed in a housing or container (e.g., electrolyte crucible).

[0036] In a variation, maintaining a closed or continuous electrical circuit, even when the sample 210 is not immersed in the electrolyte 212 may be desirable. Thus, the fixture 202 may include a conductive member (e.g., bias bar) 218, as shown in FIGS. 6-9 that extends into the electrolyte 212 before the sample 210 is immersed and / or even when the sample 210 is not immersed as shown in FIG. 5. In various embodiments, the conductive member 218 is in electrical communication with the sample holder 208 and / or sample 210. In a refinement, the conductive member 218 is a metallic or otherwise conductive structure such as bar, rod, wire, or pole. In various embodiments, the conductive member 218 cooperates with the holder 208 but they are separately moveable or are separately extendible. For example, the conductive member 218 may cooperate with a (e.g., non-conductive) tether 220 such that its movement is limited, and it cannot extend to contact certain components within the electrochemical cell (e.g., the anode or the electrolytecontainer / crucible), as shown in FIGS. 6-7. For example, the tether 220 may be fixed to the boom of the crane. In other words, the holder 208 and conductive member 218 may translate in the same direction or along the same axis / parallel axes together or separately. For example, they may travel towards the electrolyte 212 together until the conductive member 218 extends into the electrolyte 212 as shown in FIG. 5 and continue until the tether 220 is completely extended, as shown in FIG. 6) at which point the conductive member 218 cannot extend any further, however, the holder 208 may continue to move towards and / or into the electrolyte 212 to immerse a sample in the sample holder 208 (as shown in FIG. 7).

[0037] In a variation, the fixture 202 and / or boriding system 200 may include containment structure 222 as shown in FIG. 8. In one or more embodiments, the containment structure 222 provides an inert environment for boriding to mitigate or prevent oxidation of the sample surface. In a variation, the system 200 may also include a source of pressurized inert gas 224 e.g., nitrogen or argon gas) to provide a positive-pressure inert gas atmosphere in the containment structure 222. In a refinement, the containment structure 222 may be a pliable hood. In various embodiments, the containment structure 222 must be able to withstand high temperatures. For example, the material(s) of the containment structure may have high melting points such as greater than 1000°C, or even more preferably greater than 1100°C, or even more preferably greater than 1200°C. In a refinement, the containment structure may include fibrous materials. For example, the containment structure 222 may include woven glass and / or ceramic fibers. The containment structure 222 and / or source of pressurized inert gas 224 may mitigate or eliminate the quantity of available oxygen such that oxidation at the surface of sample 210 is eliminated or reduced. In a refinement, the containment structure 222 surrounds the sample holder 208 and sample 210. In the containment structure 222 may surround other components (e.g., bus bar 206, moveable arms, wheels 216, etc.) of the fixture 202. In a variation, the containment structure 222 may surround only the sample holder 208 and sample 210 (i.e., not surround the bus bar 206, moveable arms and / or joints) as there may be benefits to a smaller containment structure. For example, a stable environment may be easier to achieve when the atmosphere provided by the containment structure 222 is smaller. In a variation, the containment structure and / or materials thereof are fire and thermally resistant up to l,500°C, or more preferably up to l,800°C, or even more preferably up to 2,000°C. For example, the hood may be fire and thermally resistant according to ANSI 4950 (2024) and / or NFPA 5 IB.

[0038] Referring to FIG. 10, a method 300 of boriding is provided. In one or more embodiments, the method 300 includes providing a boriding system (e.g., step 310) including a fixture and an electrochemical cell as described herein to boride a sample, heating an electrolyte of the electrochemical cell (e.g., 320), retaining a sample in the sample holder of the fixture (e.g., step 330), applying a negative bias voltage / current / power to the surface of the sample (e.g., step 340) such as described herein, immersing the sample into the electrolyte (e.g., step 350), and inducing diffusion-based boriding (e.g., 360).

[0039] In various embodiments, the electrolyte is heated with a heater such as an induction furnace. Generally, inserting or immersing the sample or article to be treated into the electrolyte too quickly can cool the electrolyte which is undesirable and may create inconsistencies in the boriding treatment as the electrolyte temperature should be maintained or steady during the boriding process. In a refinement, the electrolyte may be heated by applying an additional heating power to the electrolyte prior to immersion to expedite the immersion process as the longer it takes the greater the opportunity for oxidation.

[0040] The intermediate stage where the sample is being immersed and prior to the active boriding stage (e.g., prior to full immersion) is particular susceptible to oxidation because of the high temperature oxygen-available environment. Applying additional power prior to immersion may permit increasing the speed at which the sample is immersed. In a variation, the additional power is reduced during immersion to maintain the electrolyte at the desired temperature and keep the temperature steady. For example, FIG. 10 provides a chart demonstrating the additional power as a percentage for samples of various surface areas. These power modification curves overcome the thermal inertia of the electrolyte volume and counter the cooling effect of inserting the sample.

[0041] The additional power correlates with the surface area of the sample. For example, the greater the surface area the greater the additional power. The additional power also is correlated to the speed of immersion. In other words, the quicker the sample is immersed the greater the additional power required to maintain the temperature. FIG. 10 illustrates the additional power needed to supplement a holding power to maintain the temperature of the electrolyte at a predetermined temperature. The percentage power ratio is shown relative to the heating speed ofthe sample as the sample is heated from room temperature (i.e., 25 °C) to the boriding temperature (e.g., 950°C) at a specific heat conductivity of approximately 0.5 J / g-°C.

[0042] In one or more embodiments, the sample is immersed at a rate such that it is immersed in less than 180 seconds, or more preferably less than 120 seconds, or even more preferably less than 60 seconds. For example, at immersion speed corresponding to full immersion in 60 seconds, requires an additional power between 140-160% of the holding power (e.g., 150%) when the surface area of the sample is 3,060 cm2and between 20-30% e.g., approximately 20%) when the surface area is 510 cm2.

[0043] It should be understood that the techniques and devices for preventing / mitigating oxidation described herein may be used individually / alone or in various combination. While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.

Claims

WHAT IS CLAIMED IS:

1. A fixture for electrochemical bonding, the fixture comprising: a bus bar; at least one arm cooperating with the bus bar, the at least one arm being movable from a first position to a second position, the first position providing a first contact area, and the second position providing a second contact area that is greater than the first contact area; and a sample holder cooperating with the at least one arm and in electrical communication with the bus bar such that a sample in the sample holder moves from a nonimmersed position to an immersed position when cooperating with an electrochemical boriding cell, the non-immersed position corresponding to the first position such that a circuit operating at a first power is formed and the immersed position corresponding to the second position such that the circuit is operating at a second power when cooperating with an electrochemical boriding cell.

2. The fixture of claim 1, wherein the second power is greater than the first power.

3. The fixture of claim 1, wherein the at least one arm cooperates with the bus bar via a pivotal joint.

4. The fixture of claim 1, wherein the arm includes a wheel disposed opposite the bus bar such that the wheel translates along an electrically conductive surface when moving from the first position to a second position.

5. The fixture of claim 4, wherein the wheel contacts an electrically conductive surface to provide the first contact area.

6. The fixture of claim 4, wherein a surface of the at least one arm and a surface of the bus bar contact the electrically conductive surface to provide the second contact area.

7. The fixture of claim 4, wherein the bus bar directly contacts the electrically conductive surface in second position.

8. The fixture of claim 4, wherein the electrically conductive surface is one or more additional bus bars.

9. The fixture of claim 1 , further comprising a conductive member cooperating with the sample holder and arranged to be immersed in an electrolyte prior to immersion of the sample.

10. A boriding system comprising: an electrochemical cell including an electrolyte and an anode in contact with the electrolyte; and a fixture having a sample holder arranged on the electrochemical cell and movable from a first position to a second position, the second position immersing a sample retained by the sample holder into the electrolyte to a greater extent than the first position and the second position providing a greater power for electrolysis than the first position, the sample acting as a cathode when immersed in the electrolyte.

11. The boriding system of claim 10, further comprising a containment structure around the electrochemical cell and the sample holder to provide an inert atmosphere.

12. The boriding system of claim 11, wherein the containment structure is a pliable hood including a fibrous material.

13. The boriding system of claim 12, wherein the fibrous material has a melting point of at least 1000°C.

14. The boriding system of claim 12, wherein the fibrous material is woven glass or ceramic fiber.

15. The boriding system of claim 11, wherein the inert atmosphere is a continuously supplied positive-pressure inert gas atmosphere.

16. A method of boriding comprising : heating a boron-containing electrolyte of an electrolysis cell based on a first power to maintain a steady temperature of the boron-containing electrolyte during active boriding and a second additional power based on an article and the article immersion rate; and immersing the article into the boron-containing electrolyte for a duration of time to form a boride treatment on the article.

17. The method of claim 16, further comprising decreasing the additional power during immersion to maintain the steady temperature.

18. The method of claim 16, wherein the additional power is based on a surface area and / or mass of the article.

19. The method of claim 16, wherein the article is immersed in less than 180 seconds.

20. The method of claim 16, wherein a negative bias voltage is applied to the article prior to and during immersing the article.

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