Background technology: titanium and titanium alloy are wide day by day because of its good solidity to corrosion Application Areas, but titanium or titanium alloy wears no resistance, and be particularly very responsive to the fretting wear damage.For guaranteeing the satisfied requirement of producing reality of titanium and titanium alloy, at the focus of process for modifying surface research the becoming researcher concern that improves the titanium alloy wear resisting property.Improve at present not following 10 kinds of the process for treating surface of the anti-fretting damage of titanium alloy: shot peening strengthening, conventional anodization, nitride laser, electrolytic coating, dry film lubrication layer, plasma spraying or detonation flame spraying layer, physical vapor deposition, organic coating, ion implantation etc.And wherein have impair the conventional fatigue property of titanium alloy base material (causing its conventional fatigue strength to reduce) up to 70% as electroplating Cr; Poor durability that has such as organic binder cemented MoS
2Or graphite dry film; What have causes titanium alloy brittle failure such as Ag or Cd coating.At present at solving Titanium Alloys at High Temperature wear resisting property difference and, being applied in the protection of titanium alloy based on solid film lubricant, hardened surface processing and this process for modifying surface of three types of soft metal coating to the fretting wear sensitive issue.But still have following subject matter: 1 titanium or titanium alloy is the metal to polymkeric substance, metal and ceramic coating poor adhesive force, and ceramic membrane that this forms with regard to making some introduce material from the outside or coating and high base strength are relatively poor.The means that 2 wet methods platings and some comprise high-temperature heat treatment process can cause hydrogen embrittlement---another hidden danger in the titanium alloy Secure Application of titanium alloy.3 wear-resisting and antifatigues are a pair of contradiction, a lot of method for surface hardening can improve hardness improves the titanium alloy wear resisting property, but having sacrificed the toughness of material, is to be cost with the conventional fatigue property (SF) that reduces titanium alloy and fretting fatigue performance (FF).
Summary of the invention: wear no resistance for solving existing titanium alloy, fretting wear is damaged very sensitive issue, the invention provides a kind of titanium alloy surface growth in situ high hardness wear-resisting ceramic coating method.The step of the inventive method is: (1), make electrolytic solution with the sodium aluminate of 3-10 grams per liter, the hypophosphite and the water of 1-3 grams per liter; (2), be matrix and with the titanium alloy as anodal, be negative pole with the stainless steel plate and both placed electrolytic solution that the control electrolyte temperature is at 10-40 ℃; (3), the make pulse power supply, in five minutes, current density is transferred to 400-800A/m
2, energising reaction 90-240 minute; (4), take out sample and promptly make finished product through washing, drying.Also can add additive phosphomolybdate or sodium wolframate in above-mentioned electrolytic solution, its add-on is the 0.3-0.5 grams per liter.Described titanium alloy is Ti-6Al-4V.Little plasma oxidation of the present invention is a new technology at metallic surface growth in situ ceramic membrane.It can directly become membrane of oxide ceramics to the matrix metal oxidation and sinter, does not introduce material from the outside, and different and general process for modifying surface makes the existing high rigidity of ceramic coating, has kept the bonding force of oxide film and matrix again.Performance evaluation of the present invention: the test of coating hardness is adopted Knoop indenter with HVS-1000 type digital display microscope sclerometer; The friction pair of the wear resisting property test of ceramic coating is a bearing steel.The present invention forms the high-hardness ceramic coating with little plasma oxidation method at the Ti-6Al-4V alloy surface, and the total thickness of ceramic coating reaches more than the 100 μ m, and wherein wearing layer thickness reaches 20-60 μ m.The maximum hardness of ceramic coating reaches 15GPa, and the frictional coefficient of bearing steel is reduced to the 1/5-1/3 of titanium alloy substrate, and abrasion loss approaches zero.The invention effect: the present invention utilizes the plasma oxidation method, directly form the high rigidity ceramic coating at titanium alloy surface, following characteristics are arranged: 1. can and change bath composition by the control electrical parameter and reconcile coat-thickness, phase composite, have purpose to improve its hardness, wear resisting property etc.; 2. this method is owing to being that growth in situ forms ceramic coating on matrix, therefore with the substrate combinating strength height.
Embodiment one: the method for present embodiment is: be electrolytic solution with sodium aluminate 7 grams per liters, inferior sodium phosphate 1.5 grams per liters and water 1; 2, with Ti-6Al-4V be matrix and, be negative pole with the stainless steel plate and both are placed electrolytic solution that the control electrolyte temperature is at 10-40 ℃ as anodal; 3, make pulse power supply is set the wave head number and is 1, negative dutycycle 0.45, frequency 50Hz, and makes positive and negative current density reach 400A/M in five minutes
2, the 90 minutes reaction times of energising; 4, take out sample and promptly make finished product through washing, drying.The thickness that present embodiment forms coating is more than the 90 μ m, leans on the matrix internal layer with TiO
2, Al
2TiO
5Xiang Weizhu, superficies contain α-Al
2O
3Phase; The maximum hardness of coating reaches 14.5-15.2GPa; With substrate combinating strength greater than 17MPa; This ceramic coating is between the 0.35-0.6 to the frictional coefficient of bearing steel, and this moment, ceramic coating was not weightless substantially and more to the bearing steel surface scratch of mill.
Embodiment two: the method for present embodiment is: be electrolytic solution with sodium aluminate 7 grams per liters, inferior sodium phosphate 1.5 grams per liters and water 1; 2, with Ti-6Al-4V be matrix and, be negative pole with the stainless steel plate and both are placed electrolytic solution that the control electrolyte temperature is at 10-40 ℃ as anodal; 3, make pulse power supply is set the wave head number and is 1, negative dutycycle 0.45, frequency 50Hz, and makes positive and negative current density reach 800A/M in five minutes
2, the 90 minutes reaction times of energising; 4, take out sample and promptly make finished product through washing, drying.The thickness that present embodiment forms coating is that 80 μ m are above, maximum hardness 14.5GPa.
Embodiment three: the method for present embodiment is: be electrolytic solution with sodium aluminate 4 grams per liters, inferior sodium phosphate 2 grams per liters and water 1; 2, with Ti-6Al-4V be matrix and, be negative pole with the stainless steel plate and both are placed electrolytic solution that the control electrolyte temperature is at 10-40 ℃ as anodal; 3, make pulse power supply is set the wave head number and is 1, negative dutycycle 0.45, frequency 50Hz, and makes positive and negative current density reach 800A/M in five minutes
2, the 90 minutes reaction times of energising; 4, take out sample and promptly make finished product through washing, drying.The thickness that present embodiment forms coating is that 50 μ m are above, coating maximum hardness 8.5GPa.
Embodiment four: the method for present embodiment is: be electrolytic solution with sodium aluminate 7 grams per liters, inferior sodium phosphate 1.5 grams per liters, sodium wolframate 0.3 grams per liter (or ammonium phosphomolybdate 0.5 grams per liter) and water 1; 2, with Ti-6Al-4V be matrix and, be negative pole with the stainless steel plate and both are placed electrolytic solution that the control electrolyte temperature is at 10-40 ℃ as anodal; 3, make pulse power supply is set the wave head number and is 1, negative dutycycle 0.45, frequency 50Hz, and makes the positive current density reach 800A/M in five minutes
2, negative current density reaches 400A/M
2, the 90 minutes reaction times of energising; 4, take out sample and promptly make finished product through washing, drying.The result of present embodiment is identical with embodiment one, but the coating that forms contain α-Al
2O
3The phase thickness layer increases.
Embodiment five: what present embodiment and embodiment two were different is, is electrolytic solution with sodium aluminate 10 grams per liters, inferior sodium phosphate 1.5 grams per liters and water, and other parameter is identical with embodiment two.Its result is identical with embodiment two.
Embodiment six: what present embodiment and embodiment three were different is, is electrolytic solution with sodium aluminate 3 grams per liters, inferior sodium phosphate 1 grams per liter and water, and other parameter is identical with embodiment three.The thickness that present embodiment forms coating is more than the 50 μ m, and the coating maximum hardness is 6.5GPa.