DEVELOPMENT OF FREE CUTTING DENTAL TITANIUM ALLOYS

本研究的目的是评价实验钛合金的磨削性能，以期开发出比CP钛更好的钛合金，用于牙科CAD/CAM。在氩弧炉中熔炼海绵钛和银、铜、铌片，制备了Ti-Ag合金(5，10，20质量%Ag)、Ti-Cu合金(2，5，10质量%Cu)和Ti-Nb合金(2，5，10，15，20，25，30质量%Nb)。使用牙科气压钛铸造机将合金浇注到氧化镁模具中。将去除硬化层(250um)的铸造合金试件(3.5 mm x 8.5 mm x 30.5 mm)以100 gf的5种圆周速度(500、750、1000、1250或1500 m/mm)在电子机头上使用碳化硅砂轮进行研磨。在最低磨削速度(500m/min)下，钛-铜合金、钛-银合金和碳化钛的磨削性能无统计学差异。合金的磨削性能随磨削速度的提高而提高。在1000 m/min和1250 m/min条件下，20%Ag和10%Cu合金的磨削性能高于Cp-Ti合金。在最高磨削速度(1500m/min)下，20%Ag、5%Cu和10%Cu合金的磨削性能均高于Cp-Ti合金。在1500m/min条件下，10%铜的磨削性能是CPTi的2.9倍左右。在Ti-Nb合金中，在较低的磨削速度(500 m/min和750m/min)下，Ti-30%Nb合金的磨削性能是CP钛的2倍左右。在合金元素含量较低的情况下，钛铜合金比钛银合金具有更好的磨削性能。

The purpose of this study was to evaluate the grindability of experimental titanium alloys with the hope of developing titanium alloys with better machinability than CP Ti for dental CAD/CAM applications. Experimental Ti-Ag alloys (5,10,20 mass% Ag), Ti-Cu alloys (2,5,10 mass%Cu) and Ti-Nb alloys (2,5,10,15,20,25,30 mass%Nb) were made by melting sponge titanium and pieces of silver, copper or niobium in an argon-arc melting furnace. The alloys were cast into a magnesia mold using a dental gas-pressure titanium casting machine. Cast alloy specimens (3.5 mm x 8.5 mm x 30.5 mm), from which the hardened surface layers (250 um) were removed, were ground using a SiC abrasive wheel on an electric handpiece at five circumferential speeds (500,750,1000,1250, or 1500 m/mm) with 100 gf. Grindability was evaluated by measuring the amount of metal volume removed after grinding during one minute.At the lowest grinding speed (500m/min), there was no statistical difference among the grindability of the Ti-Cu alloys, Ti-Ag alloys and CP Ti. The grindability of the alloys increased as the grinding speed increased. At 1000 and 1250 m/min, the grindability of the 20% Ag and 10% Cu alloys were higher than that of CP Ti. At the highest grinding speed (1500 m/min), the grindability of the 20%Ag, 5%Cu and 10%Cu alloys were higher than that of CP Ti. The grindability at 1500m/min for the 10%Cu was about 2.9 times as large as that for CPTi. In the case of Ti-Nb alloys, the grindability of Ti-30%Nb alloy was about 2 times as large as that of CP Ti at the lower grinding speed (500 and 750m/min).It was found that the grindability of the titanium was improved by alloying with silver, copper and niobium. The Ti-Cu alloys showed higher grindability at lower content of an alloying element than the Ti-Ag alloys.